Knife

The knife is the basic close quarters combat melee weapon in Call of Duty 4 and one of the melee weapons in Call of Duty: World at War. Prior to Call of Duty 4, the knife was not a commonly used melee weapon in previous singleplayer Call of Duty games (except for missions that featuring stealth and/or reconnaissance). The knife is triggered by pressing V on the PC, clicking the right thumbstick on the Xbox 360, or clicking the R3 Button on the PS3, as taught in the F.N.G. mission. On the Wii it is by default triggered through shaking the controller or by pressing down on the d-pad.

Multiplayer
The knife can be used to trigger a "Humiliation" in multiplayer maps, and will always kill an enemy player (even with the Juggernaut perk) in one stab/slash (providing it hits the target). In Old School multiplayer matches, however, two knife attacks are required to kill an enemy player at full health.

The knife is only effective at extremely close range. Using the knife to kill an enemy player will not reveal the player's position on the minimap, allowing the player to perform stealth kills without need of a suppressor. However, a knife kill is more likely to give away the player's position than using a weapon with a suppressor. When stabbing in multiplayer, the player will lunge at the target (similar to a melee attack in Halo). The knife lunge has a tendency to miss the target (even at point blank) due to lag.

Typically, there are two ways to how knives are used: pointblank stab/slash and a lunge against an approaching enemy player (walking towards the player or stationary). Experienced players will use the knife when out of ammo and indoors, but will run and gun with an automatic weapon at the first chance because of the knife's tendency to miss. In Hardcore modes, the knife is next to useless because most weapons perform one-hit kills, especially at close range.

Sometimes when performing a knife lunge and killing a player, the reciever will notice the knife is many feet away from them, yet they are still killed by this.

Trivia

 * In singleplayer, enemies don't use the knife unless scripted to do so. Instead, they will bash the player with the stock of the weapon they are currently holding.
 * In Shi No Numa if you need reviving and you're in the water somewhere (this works in the comm room), you can use your knife and your player will jump out of the water.


 * The knife used in Call of Duty 4 appears to be a SOG Bowie, and the knife used in Call of Duty: World at War is the Kabar USMC Fighting Knife.


 * If grenades or the knife or both are used exclusively in any of the Campaign levels of Call of Duty: World at War on Normal difficulty or higher, an achievement or trophy can be earned called "Kamikaze". It is worth 15 GS on the Xbox 360 or a Silver Trophy on the PS3.


 * You can only stab on the Wii version if assist aim is activated.


 * In Modern Warfare 2, the knife will be held when using the pistol, to allow a faster slash. The hand holding the knife will still be used to support the pistol.


 * In Call of Duty: World at War, it is possible to speed up reloading by using the knife while reloading when your magazine fills, opposed to waiting for the reload animation to finish.


 * In Call of Duty 4, G3 with a Silencer has an erroneously long Melee Charge Delay. The knife damage will only register 1.3 seconds after the players hits the knife button. Many consider this to be a glitch. But in fact, its just a typo made by the developers.


 * The knife will slash faster if you have no ammo in the weapon you are holding.