i know when i was being bullied at first (before i snapped and sorted it out) I used to visualise the things that I wanted to say/do to the bullies.
Maybe to get them more into it, you could get them to vent their bottled up anger against a junior wavemaster, or striking shield. Let them give it what for, and no reprimand for swearing. You will get a much better idea of where their heads are at from this, and be in a better position to help ensure that they resolve their issues with minimum need of hitting more than a target in class.
Just a thought from an ex victim of bullying.
Don't let the door hit ya' where the good lord split ya'