robam45 wrote:Is there a book I can buy that explains things like this?
Hah. Yes. There is. It's called Insignium Astartes, it lays out the markings for the entire Ultramarines chapter then follows up with examples of about 60 other Codex chapters with express statements of how each chapter denotes company including the Exorcists. Unfortunately
GW can't be bothered to actually READ it (the last codex's mini gallery was full of beautifully painted 2nd company non-veteran Sternguard, Vanguard and Terminators for various chapters). Said book expressly states that the Exorcist's denote company by colour of a helmet stripe but no subsequent depiction of Exorcists has followed that.
Imperial Armour is a garbled mess, Forge World's writers really 'get' Space Marines (in an old skool way), but the art department seem to be clueless - the Exorcist entry in
IA10 shows the aformentioned veteran with white trim & helmet suggesting standard Ultramarine markings (as suggested in the text) but the example squad (including aforementioned sergeant with white helmet stripe) has black trims but are labelled as being from the 'Tactical reserve company' which doesn't make a great deal of sense seeing as a codex chapter has two neither of which would use that colour..
Regarding sergeant helmets, its not official but as interesting obscure snippet from 2nd edition (from whence 95% of Insignium Astartes was copy-pasted textwise) was that the Genesis Chapter and White Consuls used blue as a replacement in result of helmet clashes (blue in place of white for White Consul Veteran helmets, and blue in place of red for Genesis Chapter Sergeant helmets), since both chapters are 2nd Founding Ultramarine successors and followers of the codex this always suggested that it was a 'codex approved' variation.