I've always been a bit frusterated only being able to have 16 units on the Battlefield at one time. Though I already have a hard time controling just these 16. So what I was thinking might be interesting is have seperate army groups commanded by your other generals. They used the same idea for the Historical battle of hastings where the other armies were the same faction, but commanded seperatly by the AI.

I think it would be interesting since you could command far larger armies and take advantage of your numbers. Your other generals could be given basic orders or what to do on the battlefield, artillery, attack left flank, defend hill, etc. While your AI general controls 16 units for himself, you have your 16 units to use and maybe you can switch to which general you'd like to command.

It could get very confusing but then you'd get the chance to fight much larger battles instead of small skirmishes with reinforcements. Probably to much for a patch too, maybe Total War 3, lol, just an idea.