Saintbarbido
If I'm thinking about this right, the mc is technically the first avatar now and so his avatar state shouldn't be that strong at all really. Sure it'll probably be strong compared to his normal bending even more so cause he is untrained, But since he is untrained hos avatar state should probably be very weak as well since it uses the past avatars and he doesn't know any bending movements. Unless somehow the system takes care of all those missing things cause if not then he is going to and should be very weak for a while.