Albeit it could be a bad idea (too many matches) but maybe you could add a "reset" to the grand finals? In fighting tournaments, even on grand finals, if you are coming from the winner bracket, you still need to lose twice (double elimination) in order to lose. Meaning whoever is coming from the loser bracket has to win two BO3 in order to win because they need to "reset" the bracket (since the winners bracket player hasnt lose once, they need to be eliminated twice (double elimination stays true the whole tournament)).
I agree with FtX as in that the winners bracket should have a bigger reward. Maybe Grandfinals could be a BO3 with the "reset" factor? (because the possibility of two BO5 sounds bad).
I guess what Swkoll just said lol