OH OH OH OH OH! I know this! Basically a Keyblade is formed from the person's heart. So in order to duel wield Keyblades one would need two hearts. Roxas is the only person to date that can duel wield Keyblades. I believe it has to do with the events of Birth By Sleep that he is able to duel wield. So, that would mean duel wielding is out unless your character has two hearts for some reason. And since I doubt your character going to be The Doctor I'd say we stay away from duel wielding in this roleplay.

Though I'm only co-GM so soren does have the last say in that.