Don’t issue the violent kid with another weapon. Reinforce boundaries. Tell the truth.
She’s relying on your duty and the school’s duty to tolerate her so she can misbehave.
She thinks she’s got one over on you. Being kind right now is going to hurt.
Explain you’re aware of that, tolerance continues for as long as it has to last legally, but you’re not sure she’s winning this one.
Explain that your rights are at least equal to hers, if not greater. So you and the school are looking to reduce tolerance where it damages you, on an ongoing basis. Be vague about how. Don’t converse, it’s a setting down, not a debate.
Explain no one has to tolerate her as an adult. Which is round the corner. Sad (for her) but true. Diagnosed or not. It would be nice to think otherwise, but hey.
Rebels we admire do good things, not screw others up.