Shouta
Member
A martial arts course is something I'd recommend, if anything for him to build confidence and be assertive in his everyday actions instead of looking like a target. Karate is standard flavor but it's a good route to go. However, if you do intend to have him defend himself, you need to make sure he knows the principles behind applying things he learns. There's an obvious difference practicing it in a dojo and actually applying it in a real life situation, gotta know that if you intend on defending yourself.