Hands registered as deadly weapons?

I have finally encountered someone in real life who claims that, as a consequence of his fearsome martial arts ability, he has been required to register his hands with the police as deadly weapons. He’s not kidding.

I have always assumed that this was nonsense, suitable only for movies, and bad ones at that. Yet I find myself compelled to explore this. Is it even remotely possible that he is telling the truth? Does any such law exist, anywhere in the US?

An earlier thread on this subject:

http://boards.straightdope.com/sdmb/showthread.php?threadid=179959

I stand redirected. Thank you.