Do yourself a big favor, ask your department/supervisor what the policy is for off duty training. Understand, that in law enforcement, your private life is not so private. There are lots of things that can come into conflict with the term "conduct unbecoming". Whatever the response from your department, you will at least know where you stand. If they say OK, then your covered to an extent and if they so no, then you know your on your own. I realize it's a lousy position to be put in, but remember who's behind policy making (Lawyers). I always did find it ironic.......no stupid, that policy(s) dictate the use of a weapon is approved, but if you should use physical force in the same situation, your butt can get hung out to dry.
The problem with training in the arts, is that you develop muscle memory and that will come into play in an altercation, regardless of police procedures. Most departments have very limited H2H/arrest training and most if not all is just about worthless.
Stay safe out there and remember to CYA...........