Get to the source of why He wants to hit people.
Often, its to feel the sense of dominance which comes with it, which can come from feeling inadequate or pressured. I dont know nearly enough to guess at why He might feel He needs to posture over others, but it isnt uncommon. Remember that the reason is more than likely VERY simple. If You give Him a different outlet for it, problem solved. What that is, could be anything from Creative Arts to a Punching Bag.