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With the spark of 6th edition right around the corner and Grey Knights being able to become Allies of convenience with Space Marines I got the brilliant Idea to make a detachment of the Exorcist chapter to accompany my GK into battle.

I've researched the color scheme of the Exorcists but a few questions still remain.

Would the vanilla codex be the proper book to use for the force?
And what weaponry would the Exorcists have access to, along with any vehicles?
And most importantly was there a huge gap in between the time of the GK and the Exorcist founding ( I believe the Exorcists were a part of the 13th founding and participated in the Badab war) I want it to somewhat make sense as to why these two armies are fighting together.

I have already checked the wh40k wiki and lexicanum on this topic but I figured the think tank of Dakka might help too.

They are not Successors of the Grey Knights.

This is pure speculation and Lexicanum is wrong to quote it as a fact. It is in exactly one short story, and never again mentioned outside of that.

That sounds like a cool idea. The Exorcists have a chapter devoted to them in the IA10, the second FW book on the Badab War. I'll read it when I get home and post some ideas based on that here for your consideration.

""ExorcistsEdit
The Exorcists were created during the 13th Founding, the so-called "Dark Founding" which occurred sometime between the 35th and 36th Millennia, before the start of the Age of Apostasy. The Exorcists were founded as part of a highly-classified Imperial experiment to create Space Marines who were unusually resistant to daemonic possession and Chaotic corruption because as part of their initiation into the Chapter they had actually been forced to serve as daemonhosts for a short time before having the creature expelled back to the Warp by the intervention of an Inquisitor.""

I found tis in one of the Wiki pages that seems to answer my first question about which codex to base them out of, as Vanilla marines,

The Codex: Space Marines is definitely the way to go for the start of it.

You don't have to go overboard with Librarians either, as there's nothing really which suggests they have such a thing.

As for what vehicles, etc they'd have...
It seems more likely they would be a "rapid response" force, utilizing primarily Drop Pods to ensure they land alongside the Grey Knights who they might be fighting with.

IA 10 states:

They were created in the 13th or Dark Founding and the the origin and nature of their gene-seed is cllassified by a "Bull absolute" of the High Lords Inquisitorial Representative.

Although they combat the Daemonic they are primarily a Codex Chapter unlike the Grey Knights.

Important Factors:
They are especially resiliant to Warp/Psychic attacks / terrain.
They have 12 companies - 10,11,12 are Scout companies

To represent them I would take a TDA+SS Librarian and Tac squad in Drop Pod. And for support maybe a unit of Assault Terminators with SS. They can deep strike in to support the GKs.

SS terminators will definitly be a good ally for GKs as they completely lack storm shields(aside from Draigo) and now with the changes to force/power weapons will find 2+ saves difficult to deal with.

Kanluwen wrote:They are not Successors of the Grey Knights.

This is pure speculation and Lexicanum is wrong to quote it as a fact. It is in exactly one short story, and never again mentioned outside of that.

Maybe I'm missing something, but if there's a source for the information, how is it pure speculation?

nobody wrote:

Kanluwen wrote:They are not Successors of the Grey Knights.

This is pure speculation and Lexicanum is wrong to quote it as a fact. It is in exactly one short story, and never again mentioned outside of that.

Maybe I'm missing something, but if there's a source for the information, how is it pure speculation?

Basically:
The story where it is present has the individual discussing it seemingly engaging in speculation.

There's also, again, the matter of it being present in one short story and never being repeated elsewhere.

I suppose "speculation" doesn't adequately describe the situation either.

Basically, Lexicanum likes to pretend that 40k actually has a canon and that any and all material licensed to the franchise ties into each other. That is wrong, as pointed out by the people who are actually writing said material.

If you like to see the Exorcists as a GK Successor Chapter on the basis of this one story, that is just as valid as dismissing it as idiocy. It comes down to what the individual gamer prefers for his or her own interpretation of the setting. Personally, I have to agree that the Grey Knights having any Successor Chapters doesn't really swing with what *I* 've been reading so far. But that's just me and my own preference, and I do see the point of those who would see it otherwise.

Yeah, GKs having successor chapters would really cheapen them as a whole.

The Exorcists can certaintly be seen as spiritual successors, but they certaintly don't have the Emperor's Gift as the GKs do. Claiming the Emperor as your Primarch is a privilege reserved for the GKs as is only right and proper.

So I took a look at IA10 and there is no stan-out organizational principle. It also does not even hint at the Exorcists being a successor chapter of the GK. What is does suggest is that they have a very close relationship with Ordo Malleus and that ordo may have even supported or ordered their founding.

Grey Templar wrote:Yeah, GKs having successor chapters would really cheapen them as a whole.

The Exorcists can certaintly be seen as spiritual successors, but they certaintly don't have the Emperor's Gift as the GKs do. Claiming the Emperor as your Primarch is a privilege reserved for the GKs as is only right and proper.

This is also conjecture, as it is merely speculated that the geneseed used to create them may have come from the Emperor himself.

Regardless of whether or not they are from GK gene seed they still make perfect allies for the Grey Knights as demon specialists with close ties to the Ordo Malleus.

@Bluetau in IA10 the exorcists are described as a well rounded force who work according to the codex astartes. So yes use codex SM. They also have two extra companies of scouts to cope with their dangerous training methods, so you could include more scouts to reflect this.

Also check out this GD entry:

Just stumbled over this as I was browsing the ole' Armageddon 3 website again, by the way:
http://web.archive.org/web/20061215010333/http://www.armageddon3.com/English/Campaign/Troops/exorcists.html

Nice find. I hope FW eventually gets around to filling out the fluff on these guys and other Badab War chapters as they seem to be currently doing with the imminent release of IA12.

Thank you guys for all of the info so far, I'm still researching and I hope to see some more info in IA12 when it releases. Is the Badab war book set worth the $90 or is most of that info readily available.

If you just want it for the Excorcist background, then no. They get only 6 pages and rules for a special character.

You could do-

GK Libby,

GK Termies

GK PAGK

Allied with

SM TDA Libby

Scouts

Whirlwind

+ rest of GK stuff.

That way you have the fluff (blow the S*¢t out of stuff, scouts) covered but can use the GK codex.

Regarding the Exorcists, the Ordo Malleus likely wanted a chapter on good terms with them. One that doesn't involve exterminating almost everyone who has the misfortune of fighting alongside them that is.

I had a small group of Exorcists in Rogue Trader, when they had yellow armor, but I like what FW did with them. I feel that the Badab books are worth the expense.

Kanluwen wrote:

nobody wrote:

Kanluwen wrote:They are not Successors of the Grey Knights.

This is pure speculation and Lexicanum is wrong to quote it as a fact. It is in exactly one short story, and never again mentioned outside of that.

Maybe I'm missing something, but if there's a source for the information, how is it pure speculation?

Basically:
The story where it is present has the individual discussing it seemingly engaging in speculation.

There's also, again, the matter of it being present in one short story and never being repeated elsewhere.

Who better than an Exorcist to watch over one such as Karras? Even the mighty Grey Knights, from whose seed Rauth's chapter had been born, could hardly have been more suited to the task.
Steven Parker, "Headhunted", in Victories of the Space Marines, p279 (Emphasis mine.)

That's not speculation, nor discussion; that's internal monologue.

I know that you don't like the idea, Kan, but twisting the written word to suit your argument is pretty low.

English Assassin wrote:

Kanluwen wrote:

nobody wrote:

Kanluwen wrote:They are not Successors of the Grey Knights.

This is pure speculation and Lexicanum is wrong to quote it as a fact. It is in exactly one short story, and never again mentioned outside of that.

Maybe I'm missing something, but if there's a source for the information, how is it pure speculation?

Basically:
The story where it is present has the individual discussing it seemingly engaging in speculation.

There's also, again, the matter of it being present in one short story and never being repeated elsewhere.

Who better than an Exorcist to watch over one such as Karras? Even the mighty Grey Knights, from whose seed Rauth's chapter had been born, could hardly have been more suited to the task.
Steven Parker, "Headhunted", in Victories of the Space Marines, p279 (Emphasis mine.)

That's not speculation, nor discussion; that's internal monologue.

I know that you don't like the idea, Kan, but twisting the written word to suit your argument is pretty low.

I don't have to "twist the written word to suit my argument". It is supported because my argument is that the fact that this idea is present within one short story and never repeated elsewhere is the crux of the argument.

Oh, and by the by?
It is speculation. There is absolutely no way that a random Exorcist Astartes would have information which is sealed by an Inquisitorial remit.
It's fine if you want the Exorcists to speculate that the Grey Knights are the Exorcists' primogenitors.
But it's not a definitive fact, and using one instance as definitive proof is a silly way to do things. If that were the case, then Terminators can surf on Razorbacks.

Kanluwen wrote:

English Assassin wrote:

Kanluwen wrote:

nobody wrote:

Kanluwen wrote:They are not Successors of the Grey Knights.

This is pure speculation and Lexicanum is wrong to quote it as a fact. It is in exactly one short story, and never again mentioned outside of that.

Maybe I'm missing something, but if there's a source for the information, how is it pure speculation?

Basically:
The story where it is present has the individual discussing it seemingly engaging in speculation.

There's also, again, the matter of it being present in one short story and never being repeated elsewhere.

Who better than an Exorcist to watch over one such as Karras? Even the mighty Grey Knights, from whose seed Rauth's chapter had been born, could hardly have been more suited to the task.
Steven Parker, "Headhunted", in Victories of the Space Marines, p279 (Emphasis mine.)

That's not speculation, nor discussion; that's internal monologue.

I know that you don't like the idea, Kan, but twisting the written word to suit your argument is pretty low.

I don't have to "twist the written word to suit my argument". It is supported because my argument is that the fact that this idea is present within one short story and never repeated elsewhere is the crux of the argument.

Oh, and by the by?
It is speculation. There is absolutely no way that a random Exorcist Astartes would have information which is sealed by an Inquisitorial remit.
It's fine if you want the Exorcists to speculate that the Grey Knights are the Exorcists' primogenitors.
But it's not a definitive fact, and using one instance as definitive proof is a silly way to do things. If that were the case, then Terminators can surf on Razorbacks.

Kan, your solipsism is turning into intellectual dishonesty; I suppose it's a step in the right direction that you're at least willing to admit that it's there in the story at all. It's presented in the text, not as a discussion, not as speculation, but as a statement in the internal monologue of an Exorcist marine. Nothing is said or occurs in the narrative to suggest that he is misled, or lying to himself; no assumption is required to take the statement as anything other than simple fact. As for whether it would be plausible for Rauth to know such information, the story indeed goes on to say, in the person of its omniscient narrator:

...Rauth removed his helmet... and began reciting the words of the Mortis Morgatii Praetovo. It was an ancient rite from long before the Great Crusade, forgotten by all beside the Exorcists and the Grey Knights.
Steven Parker, "Headhunted", in Victories of the Space Marines, p290

The only assumption being made here is the one that because you don't like this insignificant background detail, it can be handwaved away as speculation with a cheap jibe about C.S. Goto.

English Assassin wrote:

Kanluwen wrote:

English Assassin wrote:

Kanluwen wrote:

nobody wrote:

Kanluwen wrote:They are not Successors of the Grey Knights.

This is pure speculation and Lexicanum is wrong to quote it as a fact. It is in exactly one short story, and never again mentioned outside of that.

Maybe I'm missing something, but if there's a source for the information, how is it pure speculation?

Basically:
The story where it is present has the individual discussing it seemingly engaging in speculation.

There's also, again, the matter of it being present in one short story and never being repeated elsewhere.

Who better than an Exorcist to watch over one such as Karras? Even the mighty Grey Knights, from whose seed Rauth's chapter had been born, could hardly have been more suited to the task.
Steven Parker, "Headhunted", in Victories of the Space Marines, p279 (Emphasis mine.)

That's not speculation, nor discussion; that's internal monologue.

I know that you don't like the idea, Kan, but twisting the written word to suit your argument is pretty low.

I don't have to "twist the written word to suit my argument". It is supported because my argument is that the fact that this idea is present within one short story and never repeated elsewhere is the crux of the argument.

Oh, and by the by?
It is speculation. There is absolutely no way that a random Exorcist Astartes would have information which is sealed by an Inquisitorial remit.
It's fine if you want the Exorcists to speculate that the Grey Knights are the Exorcists' primogenitors.
But it's not a definitive fact, and using one instance as definitive proof is a silly way to do things. If that were the case, then Terminators can surf on Razorbacks.

Kan, your solipsism is turning into intellectual dishonesty; I suppose it's a step in the right direction that you're at least willing to admit that it's there in the story at all. It's presented in the text, not as a discussion, not as speculation, but as a statement in the internal monologue of an Exorcist marine. Nothing is said or occurs in the narrative to suggest that he is misled, or lying to himself; no assumption is required to take the statement as anything other than simple fact.

Other than the fact that prior to and subsequent to the introduction of this story, there is NOTHING besides this ONE SINGLE PIECE to tie the Grey Knights as primogenitors for the Exorcists.

As for whether it would be plausible for Rauth to know such information, the story indeed goes on to say, in the person of its omniscient narrator:

...Rauth removed his helmet... and began reciting the words of the Mortis Morgatii Praetovo. It was an ancient rite from long before the Great Crusade, forgotten by all beside the Exorcists and the Grey Knights.
Steven Parker, "Headhunted", in Victories of the Space Marines, p290

The only assumption being made here is the one that because you don't like this insignificant background detail, it can be handwaved away as speculation with a cheap jibe about C.S. Goto.

I don't like this background detail because it's stupid, it has never appeared anywhere else before or after this one single reference. The fact that it is taken as "definitive proof!" is as silly as those who point towards "A Thousand Sons" and the prophecy within as "definitive proof" of the Blood Ravens being Loyalist Thousand Sons.
When taken in context of the situation and looked at logically, the evidence you point towards tears the theory apart.

Could the Exorcists believe they are descended from the Grey Knights? Sure. That doesn't make it true, at all.
The Exorcists having access to the same lore as Grey Knights is not part of this issue. Your argument is that this is definitive proof.
However it is not. The Exorcists have for as long as I can remember been implied(right down to the Badab War books which support this and NOT the Grey Knight Successor Chapter silliness) to be an Astartes Chapter created at the behest of the Inquisition to serve as forces which can fight the daemonic when the Grey Knights cannot necessarily be present. That the Exorcists would have access to lore that the Grey Knights has is not proof of anything outside of the fact that the Exorcists(as per their name) were intended to be employed against the Daemonic foes that one would expect.

Steve Parker, as an author, is relatively good.
"Gunheads" was a not terrible piece of Imperial Guard fare(Guard lands, have incompetent officers with their own goals, introduce another Imperial faction with their own ends, make references to Ecclesiarchal priests indulging themselves in "disgusting appetites" with young boys, etc) but "Rynn's World" and "Headhunted" showed that he has issues sticking with something where there is in fact an established rough guideline of what he is to be writing.

That said:
If you want to believe that the Exorcists were created by the Inquisition using the Grey Knights gene-seed?
Good for you! Really.

But that does not make it DEFINITIVE PROOF where you can wave away people who say that it is speculation.

Kanluwen wrote:

English Assassin wrote:

Kanluwen wrote:

English Assassin wrote:

Kanluwen wrote:

nobody wrote:

Kanluwen wrote:They are not Successors of the Grey Knights.

This is pure speculation and Lexicanum is wrong to quote it as a fact. It is in exactly one short story, and never again mentioned outside of that.

Maybe I'm missing something, but if there's a source for the information, how is it pure speculation?

Basically:
The story where it is present has the individual discussing it seemingly engaging in speculation.

There's also, again, the matter of it being present in one short story and never being repeated elsewhere.

Who better than an Exorcist to watch over one such as Karras? Even the mighty Grey Knights, from whose seed Rauth's chapter had been born, could hardly have been more suited to the task.
Steven Parker, "Headhunted", in Victories of the Space Marines, p279 (Emphasis mine.)

That's not speculation, nor discussion; that's internal monologue.

I know that you don't like the idea, Kan, but twisting the written word to suit your argument is pretty low.

I don't have to "twist the written word to suit my argument". It is supported because my argument is that the fact that this idea is present within one short story and never repeated elsewhere is the crux of the argument.

Oh, and by the by?
It is speculation. There is absolutely no way that a random Exorcist Astartes would have information which is sealed by an Inquisitorial remit.
It's fine if you want the Exorcists to speculate that the Grey Knights are the Exorcists' primogenitors.
But it's not a definitive fact, and using one instance as definitive proof is a silly way to do things. If that were the case, then Terminators can surf on Razorbacks.

Kan, your solipsism is turning into intellectual dishonesty; I suppose it's a step in the right direction that you're at least willing to admit that it's there in the story at all. It's presented in the text, not as a discussion, not as speculation, but as a statement in the internal monologue of an Exorcist marine. Nothing is said or occurs in the narrative to suggest that he is misled, or lying to himself; no assumption is required to take the statement as anything other than simple fact.

Other than the fact that prior to and subsequent to the introduction of this story, there is NOTHING besides this ONE SINGLE PIECE to tie the Grey Knights as primogenitors for the Exorcists.

As for whether it would be plausible for Rauth to know such information, the story indeed goes on to say, in the person of its omniscient narrator:

...Rauth removed his helmet... and began reciting the words of the Mortis Morgatii Praetovo. It was an ancient rite from long before the Great Crusade, forgotten by all beside the Exorcists and the Grey Knights.
Steven Parker, "Headhunted", in Victories of the Space Marines, p290

The only assumption being made here is the one that because you don't like this insignificant background detail, it can be handwaved away as speculation with a cheap jibe about C.S. Goto.

I don't like this background detail because it's stupid, it has never appeared anywhere else before or after this one single reference. The fact that it is taken as "definitive proof!" is as silly as those who point towards "A Thousand Sons" and the prophecy within as "definitive proof" of the Blood Ravens being Loyalist Thousand Sons.
When taken in context of the situation and looked at logically, the evidence you point towards tears the theory apart.

That's the problem right there; you don't like that background detail, so like to claim that it's not there at all.

Kanluwen wrote:Could the Exorcists believe they are descended from the Grey Knights? Sure. That doesn't make it true, at all.

So... you think the author's intention was that his Exorcist character was delusional? What else from within the text would you use to support that?

Kanluwen wrote:The Exorcists having access to the same lore as Grey Knights is not part of this issue. Your argument is that this is definitive proof.

I quoted because it contradicted your insistence that, even were his chapter successors to the Grey Knights, it would be implausible for Rauth to know.

Kanluwen wrote:However it is not. The Exorcists have for as long as I can remember been implied(right down to the Badab War books which support this and NOT the Grey Knight Successor Chapter silliness) to be an Astartes Chapter created at the behest of the Inquisition to serve as forces which can fight the daemonic when the Grey Knights cannot necessarily be present. That the Exorcists would have access to lore that the Grey Knights has is not proof of anything outside of the fact that the Exorcists(as per their name) were intended to be employed against the Daemonic foes that one would expect.

None of which is contradicted in Parker's short story, and none of which contradicts his character's assertion. Indeed on the face of it, that the Exorcists should carry the Grey Knights' geneseed would seem to suit all of their previously-established background.

Kanluwen wrote:If you want to believe that the Exorcists were created by the Inquisition using the Grey Knights gene-seed?
Good for you! Really.

But that does not make it DEFINITIVE PROOF where you can wave away people who say that it is speculation.

I really don't give a toss, so here's a picture of something vastly more important: a Space Marine riding a dinosaur.

English Assassin wrote:
That's the problem right there; you don't like that background detail, so like to claim that it's not there at all.

Your statement.

It is not true.
I don't like the background detail. It's there. But if you actually paid attention, you'll note that I keep repeating a single thing.
"It is only in this one instance and never mentioned again, outside of this instance."

Kanluwen wrote:Could the Exorcists believe they are descended from the Grey Knights? Sure. That doesn't make it true, at all.

So... you think the author's intention was that his Exorcist character was delusional? What else from within the text would you use to support that?

I'm the great great grandson of Vlad the Impaler.

That's not true, but I can say it is and if I tell you I am--who are you to dispute me?
That's the point I'm making, that you keep seeming to gloss over.

Kanluwen wrote:The Exorcists having access to the same lore as Grey Knights is not part of this issue. Your argument is that this is definitive proof.

I quoted because it contradicted your insistence that, even were his chapter successors to the Grey Knights, it would be implausible for Rauth to know.

If many Inquisitors do not know, it is implausible for Rauth to know.
If the omniscient narrators of Forge World and Games Workshop both have made a point of making it clear that the information is suppressed and only available to the highest ranks of the Inquisition and that the information is purposely kept from the Exorcists themselves--it is implausible for Rauth to know.

Kanluwen wrote:However it is not. The Exorcists have for as long as I can remember been implied(right down to the Badab War books which support this and NOT the Grey Knight Successor Chapter silliness) to be an Astartes Chapter created at the behest of the Inquisition to serve as forces which can fight the daemonic when the Grey Knights cannot necessarily be present. That the Exorcists would have access to lore that the Grey Knights has is not proof of anything outside of the fact that the Exorcists(as per their name) were intended to be employed against the Daemonic foes that one would expect.

None of which is contradicted in Parker's short story, and none of which contradicts his character's assertion. Indeed on the face of it, that the Exorcists should carry the Grey Knights' geneseed would seem to suit all of their previously-established background.

Except it doesn't.

The whole point of the Exorcists is that they are a force which is not consisted of psykers and not independently minded like the Grey Knights.
The whole point of the Exorcists is that they are a force which is your average Astartes force, but with the caveat that they are supremely effective in combating daemonic incursions due to the fact that they willingly expose themselves to possession and then have to cast it out. If they fail in that--they're executed.

Kanluwen wrote:If you want to believe that the Exorcists were created by the Inquisition using the Grey Knights gene-seed?
Good for you! Really.

But that does not make it DEFINITIVE PROOF where you can wave away people who say that it is speculation.

I really don't give a toss, so here's a picture of something vastly more important: a Space Marine riding a dinosaur.

So basically, you're employing the Chewbacca Defense.

Well, have fun Johnny.

Kanluwen wrote:

English Assassin wrote:
That's the problem right there; you don't like that background detail, so like to claim that it's not there at all.

Your statement.

It is not true.

Oh really..?

Kanluwen wrote:The story where it is present has the individual discussing it seemingly engaging in speculation.

You'll find that's precisely what you were doing right there. It's not presented as "discussion", it's not presented as "speculation"; it's the internal monologue of a member of the chapter in question, and you are being - deliberately or out of ignorance - misleading to claim it to be otherwise.

Kanluwen wrote:I don't like the background detail. It's there. But if you actually paid attention, you'll note that I keep repeating a single thing.
"It is only in this one instance and never mentioned again, outside of this instance."

Which would be relevant if there were reams of published material on the Exorcists. Steve Parker's two stories in fact make up a significant portion of the extant fluff featuring them.

Kanluwen wrote:I'm the great great grandson of Vlad the Impaler.

That's not true, but I can say it is and if I tell you I am--who are you to dispute me?

I don't know why I'm dignifying this with a reply, but in this instance, your internal monologue would go: "I'll something irrelevant about Vlad the Impaler because I can't come up with an intelligible argument.". How do you think this is relevant?

Kanluwen wrote:

English Assassin wrote:

Kanluwen wrote:The Exorcists having access to the same lore as Grey Knights is not part of this issue. Your argument is that this is definitive proof.

I quoted because it contradicted your insistence that, even were his chapter successors to the Grey Knights, it would be implausible for Rauth to know.

If many Inquisitors do not know, it is implausible for Rauth to know.
If the omniscient narrators of Forge World and Games Workshop both have made a point of making it clear that the information is suppressed and only available to the highest ranks of the Inquisition and that the information is purposely kept from the Exorcists themselves--it is implausible for Rauth to know.

Source? Because all I can find on the subject, in Imperial Armour X, is that their nature is classified by the Inquisition, and nothing to state that either the Inquisition nor the Exorcists are ignorant of their heritage. Unless you can point to a source, all that guff about "the highest ranks of the Inquisition" is the product of your imagination, and, though doubtless fascinating, not germane to this discussion.

Kanluwen wrote:

English Assassin wrote:

Kanluwen wrote:However it is not. The Exorcists have for as long as I can remember been implied(right down to the Badab War books which support this and NOT the Grey Knight Successor Chapter silliness) to be an Astartes Chapter created at the behest of the Inquisition to serve as forces which can fight the daemonic when the Grey Knights cannot necessarily be present. That the Exorcists would have access to lore that the Grey Knights has is not proof of anything outside of the fact that the Exorcists(as per their name) were intended to be employed against the Daemonic foes that one would expect.

None of which is contradicted in Parker's short story, and none of which contradicts his character's assertion. Indeed on the face of it, that the Exorcists should carry the Grey Knights' geneseed would seem to suit all of their previously-established background.

Except it doesn't.

The whole point of the Exorcists is that they are a force which is not consisted of psykers and not independently minded like the Grey Knights.
The whole point of the Exorcists is that they are a force which is your average Astartes force, but with the caveat that they are supremely effective in combating daemonic incursions due to the fact that they willingly expose themselves to possession and then have to cast it out. If they fail in that--they're executed.

I too have read Imperial Armour X - indeed I seem to have paid better attention to it than you. Did I (or for that matter Steve Parker) claim that the Exorcists were all psykers? No, indeed the Exorcist character in his short story isn't. The Grey Knights solely recruit psykers; as made clear in both 'Headhunted' and Imperial Armour X, the Exorcists don't. Again, where's the inconsistency?