I eventually settled with the Psyker for my Inq28 warband for the Chapel on being an Astropath.
I have a very vague recollection of a green robed Astropath artwork from the original Warhammer 40k Rogue Trader game book (or perhaps it was the old wacky 40k expansion for Talisman), but I haven’t been able to find any copies of it online as a reference. Most of the more recent official colour schemes are a dark green so I decide to stick with that as a base colour for the robes and then a copper metallic chest-plate and staff which ties back to the power armour colour of my Inquisitor Kallidon Fell. As I think I might have mentioned previously in my blog, I am really a quick and dirty army painting by numbers guy at heart – I’m pretty happy churning through when I have a simple scheme for an army down, but I do struggle trying to do something a bit more nuanced like individual characters. I think with Fell’s warband going forward, I’ll try to make sure that they all share the copper metallic as a spot colour to very slightly tie them together, but I won’t worry too much about it if they don’t look too cohesive as a group as they are supposed to be a collection of loosely aligned individuals rather than an army.
Atellus is proto-typical for an Astropath: blinded from the sanctioning/soul-binding with the Emperor and prematurely aged due to the ravages and strains of utilising his powers. I decided to keep the slightly damaged hand and just discolour it slightly to indicate an old wound or perhaps withering due to sanctioning or a very slight hint at warp taint. If it nags at me too much then I might come back to him, clip the hand off and glue a new one on.