I can equip Cait with all kind's of different gear, armor, weapons, etc. Nick on the other hand can't wear anything. All I wan't to do is dub him the new silver shroud. Whats up with that? Can Nick wear anything?

I never did find anything that Nick would wear. At one point in his dialogue, he mentions that his outfit is a very deliberate choice - that part of what it took to be accepted as a citizen and PI despite being an obvious synth was making sure that he looked the part.