As stated before, the whole point of heavy armour was to stop lighter blows from getting through. Either use your bow/crossbow wisely (i.e. aim for head or feet), or boost your power strike. If you aren't a very strong character, use a weapon that works (blunt). If you don't want to do that, accept the fact that you aren't a character that can beat a fully armoured knight and let your army do it for you.
I take on top tier troops one on one all the time. I have heavy armour so I can't dodge, I just block, then smash them in the face with a sledgehammer, sometimes it takes two or three blows, but then these are top tier troops, what do you expect?
Fighting in the front line is where all the fun is, having your men stand behind you whilst you go out alone to face the enemy commander charging his horse at you is exciting. So you have to be smart about it, with my armour I always have to keep an eye out for blunt weapons. When unarmoured, keep an eye out for everyone. And when crap happens, I can heal myself, and when it's too bad for that, high wound treatment and iron flesh are your friends.