in terms of trying to get him to realise his behaviour, have you tried using your phone or camera to record him when he's doing it, and then sitting down with him and watching it together, when he's calm?

people are often really, really surprised to see how they've behaved etc when in a rage (or drunk, drug affected, etc) and actually showing them can be so much more powerful than telling them. And hearing your girls tell him how it made them feel after watching it back may also be quite powerful.

Not that the point is to give him a guilt trip, but if he feels convicted, then he'll have more strength to catch himself and modify his behavour next time.

And while martial arts may be about fighting, it's not about violence - discipline combined with physical exertion might be the perfect combo for him, to get rid of some of that teen angst and pent up frustration...

good luck!!