Well I am a lover and a fighter. Versatile.
I don't hit people outside martial arts.
I like the idea of sprint-sliding into someone's knees to trip them over. (But mids should be best at doing it.)
The idea of Heavies just being able to push over an enemy sounds good. I'd like a good 1st person knockdown mechanic for melee attacks, with only knives doing any substantial damage. I mean, in RL a melee shove wouldn't be more powerful than a bullet, but it would have a higher chance of simply knocking someone over with force. Unless you're talking about shotgun shells and the like. So, a knocked down enemy should be disabled for a second or so while they get up, giving you an opportunity to knife or shoot.
For me, Mirror's Edge had a disappointing combat system. A punch combo, a kick, a different kick, or a different kick. And the disarms.