If you're going to leave the plate armor in (or even use antagonists in heavy brigandine), your footmen need to go to either awlpikes or halberds - something that will punch holes in armor, even if it's a generally less effective weapon. That or fewer polearms and more axes or hammers of some variety - the Vikings chose axes for a reason.
Heavy axes and hammers do a number on armor, as do certain crossbows. The crossbows are generally restricted to footmen (at least the ones heavy enough to do what I'm talking about), but axes still work pretty good from horse. And of course, couched lance always sends a message, no matter what you're wearing. Really big swords can be effective against both horse and armored rider, but they have to be BIG swords ... just slashing at them with your 3-pound longsword will likely just make them angry.
Just don't go out there with some kind of saber, or a stick or something, and think you're going to cut down the human tank. It just won't happen.
(I did allow halberds and other heavy polearms to be used to slash from horse, as the Lucerne Hammer and Bec-de-Corbin were ... but they're so clumsy that you probably don't want to try that. It took a while to get the speeds tweaked where that would behave right. The RCM lets you do a few things that you will later find to be a bad idea.)
And yeah, any more balance ideas, I'll try to help.