Just one. http://tinyurl.com/7vuhbkd Thorn Gauntlets increase all Fist based damage, including claws.. and will barely be noticed upon your cosplay. Good hunting.
Mhmmm Test it first though. I know for positive it effects Caestus, and Dragon Bone fist, but I've never tried claws; I just see no reason it would differentiate inbetween the 3.