Sorry, but I haven't seen anyone discussing this, even though there are plenty of knife topics.
It is my understanding that, if you don't have a secondary weapon selected, then you will automatically use the "combat knife" as your secondary. However, you can still knife someone when your primary is out. So there has to be a difference between "normal knifing" and the "combat knife"...right? Or am I missing something? Anybody know?
I'm guessing it's at least faster - kind of how the melee knife you use with a pistol in MW3 is.