It's actually not true. It's a complete fabrication made up by several bullshido grand masters. The courts do not consider a martial artist's body to be a lethal weapon. All they look at is the circumstances of the assault and the level of force applied.
Basically a black belt, a boxing champion, and a drunk all get the same charges if they beat someone senseless with their hands. Their is no difference under the law. Assault with a Deadly Weapon actually requires a weapon to be present.
That is not dead which can eternal lie and withs strange aeons even death may die.