Just simple upgrades to make the battle easier, or that change add a gimmick that changes the gameplay, rather than get A but lose B. I think letting the player break a game with cool features and skills is better than pulling the leash like "hey lets not have too much fun now, okay?", like the game is you vs us, rather than you giving us a toy to go wild with.
On a more serious commercial product I can see how the balancing might be a serious thing to work on, but on smaller jam projects like this, it could be more fun for players and more of a learning experience to you to let it break, if it is to break. Like salt on food, when you put too much its over, but when you put too little you can just add some (in this case, being less restraining is the metaphor)
