Hey, I recently stumbled across this game and decided to give it a whirl despite the whole chapter 19 thing. It was a lot of fun! Some balance things I've noticed:
-The cannoneer you get is absurdly good. Absolutely trivializes so many parts of the game and many bosses. I really loved bullying things with them, but they're definitely really over tuned
-Cupid bows are insane. Charming a godslayer and then having it turn around and kill the chapter boss by itself was so funny. If used on the bosses themselves it basically negates their enemy phase attack and prevents them from switching weapons. Makes it really easy to pick them off with whatever character you need to raise.
-I didn't get a lot of time to play around with it, but the tradable +2 move accessory seems nuts. Being able to give boots to anyone when they need it and then trade it back when they don't just feels crazy to me.
If you do ever come back to this game I would actually recommend not balancing these things out. Using these and other busted tools was a ton of fun, and honestly made the game stand out more than it otherwise would.