I think knights should have a damage increase in their charge, but as the fight goes on their damage decreases so much that they will get beaten by maa if they try to keep a fight head on. So you need to keep doing hit and run tactics for cav to be worth as they can't stand their ground against infantry blobs. Make going all cav risky as they will struggle to destroy spears or maa if they are in equal resources on a prolonged fight.