I love your ideas, but I would strongly suggest running the numbers for how much damage these weapons would actually do. What do you expect endgame PA MA and Speed to be, on average? Once you set down a good base, being able to see exactly how much damage each weapon can do would make it MUCH easier to balance.
As for the Tonberry Knife, it is a great idea, I was wanting to do the same thing, now I feel like a copy cat.... As for balancing it, how much HP, on average, do you expect knife wielding characters to have endgame?
