Normal battle difficulty is way too easy, but hard battle difficulty where my faction leader dies when he charges into a group of peasants is absurdly difficult. I suppose what I really want is for the AI to use better tactics, for my units to rout a bit easier, and for their units not to rout as easily -- I don't want the damage changed where general's bodyguards / generals poke a peasant and die. I'm not using against mods if there's one that solves this problem.
I'm playing on Very Hard campaign difficulty as well, and the rebel spawns are just aggravating. From what I've read there's no way to fix that, but if there were a way to get a more aggressive/intelligent AI without changing the difficulty and consequently increasing the rebel spawns that would be awesome.