Stay in your bubble, just like OP. Because let's be honest, she's not looking for advice, she has already made up her mind. All she's looking for is for people like you to tell her that it's okay. When it clearly isn't. And god forbid, when a man does come at her (sexually or not), she's not going to be able to reach for that knife, because she'd just freeze there and then. And if she does manage to reach for that knife, what good does it do when she doesn't know how to use it. She'd just be inviting more trouble for herself.

What advice you should've given to her instead is to learn some self defence techniques and do some adrenaline drills, so that she's ready for such a scenario, to run as fast as she could to protect herself. I know how this sounds, but don't get into a fight that you can't win. That's what you should've told her, as a woman. But no, you let your hate for this city and its people get the better of you and cloud your judgement. Because feeding into her idea by saying that it's a 'city of rapists' ain't the way to go.