Hey, here's an idea:
Too complicated, too much work, and too useless. How about we just hit people with the sword and not throw it at them? Yeah, that's a good idea. It would sure as hell take a lot of code, at the end result would be crap-tastic. Either an instagib that people would abuse in close up melee, by just chucking their sword instead of using regular melee, or a worthless attack that would almost always throw your sword out of the map, or just stick in your opponent while he comes swooping after you. Big whoop. Melee is going to be improved in 1.2; until then, don't worry about changing the mod around completely to let Trunks throw a damn sword. He doesn't do it on the show, so why should he do it in the game? He would probably have horrible aim anyhow, seeing as how he never trained with it.