Here in California we have the concept of ADW, an assault with a deadly weapon. Almost anything can be considered a deadly weapon if it is used that way, including martial arts training.
Yes, and (according to my law student ex) "deadly force" is commonly defined in US jurisdictions as force that could (not necessarily did) result in death or serious bodily injury
. Hence, if you break someone's arm or dislocate their shoulder, you could be said to have used "deadly force". Funny how little common-sense definitions are worth in court.