you're in for some balls in the face
Assuming nude combatant has balls...
Vulnerability to biting aside
? So is he going to put his balls in your face, without being bitten, while he bites your balls in his face?
being naked prevents one from being easily grabbed (clothes, etc)
hair? shaving, or lubing oneself, is work, and not necessary for nude combat. Also, one can use slicker closer-fitting clothes (arguably less prone to being grabbed, especially if made of the proper material, and well-lubed)
being naked ... allows for full range of motion
There are clothes which allow this, too.
scatter some broken glass around, but if ... he's wearing shoes, then you're doomed
Or, knock him to the ground.