I read somewhere that they are bringing in a new melee system. Like being able to counter a riot sheilder with a sledge hammer. I also read that it is going to take more than 1 swipe to kill with a knife, but thats besides the point.
What I want to get into is the mechanics of knifing/lunging. How many times have you had someone knife you through a hailfire of smg bullets? Or pounce on you through a 12g blast. My solution is this. Players cannot knife when a certain amount of damage is received or if certain body parts are hit. kind of like how in Gears 2 the chainsaw bayonet lowers when you are being shot.