If you could actually manage to get 256 people signed up it'd be something to see. Keep it simple with only 2h, 1h, and spear imo. Before the recent tourneys, I would have said spreading the tourney over a few weeks would be better but after seeing how they went I'm not so sure, and tbh a 1 day duel tourney which has lots of players would be cooler.
Also please no joust, that just sounds annoying. I'd remove any blunt weapons like morningstars and hammers and the like, because that's pretty **** to watch, not to mention overpowered. Generally, 2h will beat spears and 1h but when you do see duels that aren't just 2h V 2h, they're usually engaging (and I'm confident someone will choose spear/1h anyway).
Something else I was thinking about- if you're going to have it on one day, for the love of god make things speedy. Nobody likes waiting around for no seeable reason. I'm talking about quickly setting up brackets, quickly deciding who's playing who, and having multiple arenas for people to fight in, at least for the lower-level fights. I probably don't have to tell you this but just please keep it in mind