Re: Anger on the mat
Unlike most others, who seem to read a general bad state of dojo conditions from your lines I would not go so far to talk about tolerated abuse. Ok, this guyīs not in complete control, thatīs bad. Ok, sensei is not able to adress and manage it, thatīs not very good either.
But from your lines I also read a great sensitiveness on your side. I guess you donīt like to deal with anger, especially if itīs directed at you. Aikido is also about dealing with aggression, not only doing nice movements in harmony, itīs more. So maybe the is a chance in this for you for your own development.
Talk to your Sensei. He should know whatīs going on with his students, even if he wonīt change the situation as you would like.
If someone is getting into anger, adress this anger. Especially this guy seems not to be competely beyond rason.
Refuse to train with people, who you fear to hurt you and tell them why.
Only if you have to fear getting hurt sooner or later, leave the dojo. Safety first.
best wishes !