derpy derp derp.
You know that Zombie Face Rape attack? where theres visible evidence of a Zombie Biting You circuits out?
Well, when that happens, you get the Zombie/Kill status, where the game takes over your avatar for a couple of seconds and starts attacking your team.
When your infected, you no longer have use of your weapons in that time (duh, what happens if a bomber gets infected?)
What happens is that the knight starts using his big ole hands to start swiping at his buddies.
They also start making zombies sounds and get the zombie persona. (limpy limp biscuits)
after 5 seconds of infection, it wears off and the knight can go back to slashing.
p.s. i may or may not have gotten the idea from Nickblades suggestion.
Language, sir.