Re: Anger on the mat
You can only affect how you respond to anger directed at you. The angry person is responsible for their own feelings and actions.
Sensei should be aware of the class dynamic, or a particular students attitude and "manage" it as necessary for the good of the individual, others in the class, and the overall health and welfare of the dojo.
You should not train when angry, nor train with people you are uncomfortable with. It is not always easy to say "no" but sometime necessary I suppose.
One thing for sure, anger met with anger will only produce more anger.