The First Sinner runback is lowkey the worst in the game. It's the one boss you actually respawn at if you die, but none of your tools replenish. So you have to go all the way back to the bench and come back every time if you want to use your tools.
Wtf were they thinking? Could have just put a bench right outside the boss entrance. But this is basically the first flaw in an otherwise flawless game, so I digress.
Welcome to your Divinity.