ok so i was wounding about two things one i found some girl in the gem cave and after you beat her you get nothing and how do i unlock the cell in the jew castle 2 dungeon floor you know  where you enter a hallway and found a person who ask you to find a switch or key to unlock it where to i find the key for the cell? edit to find her you need to go to two giant gems in and cracks all over the wall and floor

So the secret boss fight is just there for fun, you can rebattle her as much as you'd like. Also no need to worry about re-entering the castle. The only people you can free from the cells are the Jewish men during the story segment. Hope this helps!

it did thank you