The first thing to consider, as far as Harley was concerned, was that if it was Jonathan, he'd want revenge. Aside from any other torture he would have planned for her, aside from anything else he'd want to do to her, there was one thing that he would absolutely insist on doing. It was the reason she'd run off in the first place, and the reason she'd been able to get away. She'd staked him, and he would never let that go. He'd want to put a piece of wood in her heart. So she needed some protection there. She needed to be able to survive if he attacked her physically.
Bone is thick, but Jonathan had the strength to punch through it easily. She couldn't rely on metal armor for the same reason. Harley knew how strong she was, and knew that Jonathan was orders of magnitude stronger than she w
