It's highly unnecessary to state that 'no jumping', I'm pretty sure the majority of the dueling community can pull of a 'swing' if his/her opponent is jumping. It's not unbeatable, and some don't mind it being in the tournament - you're making this tournament look more like a joke than a competative 1 versus 1 duel.
I don't know if you are daily on duel servers, but I'm guessing - you should try it, come on once or twice, see it for yourself. No one is abusing jumping, jumping doesn't make your sword faster nor does it make you immortal - there's nothing wrong with jumping, please reconsider the rule before your tournament flushes down the toilet.