I have heard of this happening to others when a disguise is used. Thats what the gauntlet is a disguise. How it works is a disguise property is added to the items .uti which will change the wearer into an npc.
I have never seen this happen myself and I have used many disguise mods in the past. Normaly this would not happen and the disguise would be removed with the item. I have not figured out why this is happening(to be honest I haven't looked into it) the change is almost certanly permanent from others experience with this problem.
Lucky you though, thanks to tk102 and his savegame editor (
http://www.pcgamemods.com/5862/) you can change carth back into what he should look like or you could turn him into a jawa ;) it's your choice.