What I had in mind was a stealth suit, close-fitting and enchanted to provide an armor bonus, similar to robe of the magi. Would he still be able to benefit from his vest, though?
On a similar vein, I thought it would be neat to make the suit from a combination of shadow spider silk and adamantine (made into extremely thin wire). This would be it's a bit stiffer than regular cloth, but perhaps still benefitting from the DR 1/- of light adamantine armor, or maybe even the axeblock/spearblock properties. This would probably force it to be armor though (albeit with 0 or 1 base AC), and have a max dex mod, which would make it counter-productive, but I still love the idea



