Well, he can't steal her keystone, that's mystically cued to her and doesn't even physically exist most of the time. And if she's got a vanitas she'd keep it safe at home. I doubt she'd have any deathmasks or memorabilia - those are more powerful and harder to get - but she's got some charms and c'mon, dude, that's a fetter, that's got a ghost in it. What do you want a ghost for, you're a bird.