How to become a martial art master?
1/Find a master who live in the middle of nowhere and spend years training everyday all the day.
2/ Buy a reference book.
gaolang : my fist shatter, i can't box anymore
saw paing : did you know if you bash your bone with hammer, it will grow stronger?
gaolang : nice advice mate
Is that spoiler real? Because I figured that was a possibility, but when you consider that boxing has restrictions on the weight of your gloves and that it's against the rules to put hard things in them, I would assume that what you're talking about would be against the rules. Heck, every boxer would go through such a procedure before getting injured if it was allowed. (Although to be fair, you don't want to add such things that can be grinded down because you do not want that stuff in your bloodstream. It damages your nerves.)
I just hope he strengthen to the max his bones to the point of not being able to break or some ridiculous shit like that. If he implemented some metal stuff inside that would be the end of the boxer and kind of sad for that character.