I gave my word, Lucy. Would have kept it even if you were a powerless demon like the rest of us.

The good news is that she's aware of what she is, wants it gone and is aware it could be used against you. She's more concerned about you acting like a fool, getting yourself hurt due to her. You found yourself a decent human.

How do you want to proceed from here? I don't want to pull something out of her that might be her just because she wants it gone so you don't get hurt.