I would avoid the sword completely in airsoft, CQB or not. Realistically, you don't see knife kills all the time usually once or twice in an all day event. As for throwing the knife it depends on the players and the host. They are pretty widely accepted but not completely. If the host is cool with it then by all means bring the knife and throw it to your hearts content, obviously be safe with it though. Odds are you'll be out before it leaves your hand though.
Disco said it pretty well, you are basically bringing a knife to a gun fight so don't expect to get many kills.