I managed to actually finish this guy off the other day. Although, as usual, I might well go back and do a bit more, when in all probability I decide I'm not happy with how he's turned out afterall...
Sorry for the dodgy photography, which is in places, blurry. But I'm not forcing you to look, so you've no cause for complaint (right?)...
Well, here he is. As you can see, I've taken a different approach to weathering the metal areas than the one I use on my Death Guard. I figured that cultists would have access to a far lower standard of kit than space marines would, such as Imperial Guard or PDF type items, which would theoretically degrade in a different manner.
The preacher, here for example would be carting about stuff that he'd nicked from an Ecclesiarchy shrine for desecration purposes, etc. The censer that he's carrying, I figured would be made from some type of soft precious metal, so I've just tried to generally scum it up with a grey-greenish matt finish, and a light tarnish.