At the moment, not every slot in the customisation is being used but more stuff will be added in later updates.
To beat the sword girl, I recommend buying lots of mushroom soup from the shop and using a bow or other projectile weapons if you're finding it hard to defeat her. Also, make sure to dodge roll if boulders are dropping where you are to avoid getting hit and try and get behind her before she shoots the laser, cause she takes a while to charge her laser, leaving her exposed from behind. Hope that helps and good luck.👍