The Combat Knife should at least be decent. Knifing while holding a gun shouldn't be a valid alternative to shooting, but if you're intentionally using just a knife, you should be able to kill somebody.
What is your definition of dependable? Are you wanting Commando from MW2? If anything, it still needs to be toned down. 2 hit knife from the front, 1 from the sides and back. I made the switch to Hardcore after putting 4 hit markers on a rushing 'ninja', only to die on his blade. Only in 'Core' does knife>bullet-to-your-face.
GT - Nightshade vII PSN - ArtfulDodger 213 ~ "I live in the weak and the wounded..."
The panic-button knife shouldn't be in at all. Combat Knife should have been defaulted to LEFT on the D-Pad. And it should be a dependable way to kill someone. Since it requires you actually go through the thought-process; "equip knife, click melee, profit?"
But, no, the panic-button should have no range, no lunge, and only lock-on when the person is within 120degrees of your eyesight, and your basically surprise butt***ing them.