As a new
DE player my first suggestion to you is to avail yourself of the
DE Tactica here on the site (the link is in my sig) you'll find a lot of advice on basic builds for various units (which is really mostly what I'm saying to you in my review below). I'll also reasonably agree with much that has been said before as far as the relative competitiveness of footslogging
DE. That said I'm content to regard your list 'as is' and just try to give you some thoughts on how to improve it within the concept you are already going with. So, with that idea in mind here are my thoughts;
Destroid wrote:HQ
Archon
Shadow Field
Agoniser
105 points?
Common mistake - re-read the codex as far as his wargear options and then spend the extra point to buy him a splinter pistol.
Beyond that I think your weakness here is two-fold. First, you're burning a lot of extra points to make him an Archon which you really don't need at 1500. I'd advocate dropping him to a Dracon who is basically just as good and will save you enough points to buy more wargear for him (or maybe Raiders for mini sniper squads...

to clthomps).
Second, as mentioned, more wargear - specifically combat drugs. With drugs he is a close combat machine of death, without them he is a moderately dangerous
HQ choice. Get drugs.
6x10 Warriors
6x2 Dark Lance
The biggest weakness I see here is lack of mobility. I absolutely adore sniper squads but I find they work best as part of a force rather then the focus of it. If you have the models you could really benefit from turning some of these into mini sniper boats or even upgrading one or two to assault squads who will be able to move across the board and engage and claim enemy objectives. The extra anti-infanty nature of an assault squad could also help, and you could even go for a 'kan wall'
DE concept and shield the assault squads with the Talos.
9 Wych
2 Blaster
Raider
In the final analysis all your Wych squads are really the same so I'll just abuse them all at once. First off I will note that your math is wrong (I calculate a 10 man Wych squad in a Raider with 2 Blasters as 185 not 167)
Now, you are also fielding your squads in a way that suggests you are not familiar with how and why Wyches work. I will advise you to go check out the
DE tactica again but in short you're really not optimizing them if you field them without Wych Weapons and also without a Succubus with some form of power weapon. I would strongly advise you to trim down a couple Wyches from each squad to afford these upgrades and/or use the points from the Archon to Dracon switch. If you are running them only to help tarpit stuff for your gunline then trim down the number of Wyches as you only need 5-6 to be a speed bump.
3x Talos
3 Talos footslogging? Well, maybe it will distract your opponent from your 3 Raiders a bit, so you'll have to try to talk them up a lot and basically drop them dead front and center aiming for his lines. My biggest concern here is you almost need all three to manage to distract anyone and at the same time you really need at least one to stay behind to help guard your gunline from outflankers. If you really love the idea of 3 Talos in your army I will suggest that you might wish to look into Webway portal lists for your army, as those are optimal for getting the Talos into the battle.
Pretty demented army... I figure the 12 lances should take care of any armor (+3 after vehicles drop the wyches), wychs assault anything that looks vulnerable to them... Talos for marching down the board being a menace.
Should tear MEQ a new one and dominate mechanised armies... orks could be a problem, but their vehicles should all pop fast, a combined talos/wych assault should do good things to the remainder. Splinter rifles will be effective for killing boys that try to close to within shooter range and dark lance/blaster will instagib bikers and helicopters.
15 Lances is not a bad amount of lances, though I will note that with how stationary your 6 sniper squads are your ability to use all of those shots will be situational depending upon the terrain, the deployment type (your
DE will not be fond of
DoW or Spearhead methinks) and also will depend on your opponent's army. I see your biggest issue to be dealing with either
DE or regular E as both races will usually be very mobile and fast and will be able to limit your ability to bring your lances to bear on them. Pod Marines will also be a little rough to deal with.
I will also add that the Talos is not that great at killing Orks since usually ork mobz have a power klaw in them, and the Talos is quite vulnerable to power fist/klaws.
I actually see your biggest challenge being mech
MEQ. They can work angles to limit the number of lance shots they receive. Your Wych squads are only going to be able to maybe tarpit
MEQ since
Str 3 and no power weapons does not impress the manly Marines in their 3+ armor, neither do splinter rifles. That leaves you lances and blasters and your
DE lord, non of which (save the Lord) can really kill that many marines in one go. You are also right to be concerned about horde, as your anti-horde tech is very weak. Do not trust in splinter rifles on footslogging squads because by the time you can shoot enough splinter rifles to really hurt an Ork mob then you are within range of the Ork mob to assault you.