The Tactical Knife attachment allows the character to hold both a pistol and a knife at the same time, letting the player stab about twice as fast. The Tactical Knife can be used with all handguns, although in the single player campaign it is only used with the USP .45 by default. The ability to knife faster and more frequently is advantageous in close quarters combat. The Tactical Knife attachment seems to offer no downside whatsoever versus the base weapon, with the exception of increasing visual recoil on USP .45 and M9, which may disturb the player's performance. It does, however, correctly align the Desert Eagle's iron sights when attached. It will slightly misalign the USP .45 sights. In Multiplayer, a common setup for the Tactical Knife involves the Marathon, Commando and Lightweight perks, and a pistol of the player's choice with the Tactical Knife. Many players will abuse Commando Pro's extreme knife lunge range, combined with unlimited sprinting and moving faster than normal players in this fashion to get a large amount of kills.
Tactical Knife, as shown in an early demonstration of Cliffhanger.
The final version of the tactical knife. Note the angle the knife is held at.
The Tactical Knife attachment returns in Call of Duty: Modern Warfare 3, being functionally the same, and once again, exclusive to Pistols. It is unlocked at weapon level 7. On the two revolvers in MW3, unlocking The Tactical Knife brings the weapon level to 10, the maximum for the normal pistols, since Extended Mags isn't available.
The Tactical Knife attachment returns in Call of Duty: Black Ops II. The tactical knife is unlocked at weapon level 9 for the pistols. It performs similarly to Combat Knife as it has a little lunge and can be used more rapidly than the standard knife.
The Tactical Knife returns in Ghosts. Unlike the regular Combat Knife, the Tactical Knife does not immobilise the player for a few seconds when stabbing a target, generally making it a preferable choice over the standard Combat Knife.
The Tactical Knife returns in Call of Duty: Advanced Warfare. It is available to all pistols and the M1 Irons.
The Tactical Knife is more forgiving if the player misses than the Exo melee or the Combat Knife, due to its quicker animation and recovery. It is more silent and less sound-recognizable than the Exo melee, however the Tactical Knife's tighter hit box means the player will have to be facing the target directly.
The Tactical Knife returns in the event "The Resistance" for Call of Duty: WWII. It was exclusively available to the Resistance Division, which also debuted during the event.
On April 10th, 2018, the Tactical Knife was removed from the Resistance division and became a standalone attachment for the Handgun class.
When the Tactical Knife is out with the player's pistol, the latter will gain a much larger zoom.
In Multiplayer, the Tactical Knife has no third person model. Players will look like they're holding a pistol with no attachments. Also, the Tactical Knife uses the same melee animation as generic melee in third person. However, in Call of Duty: Black Ops II this was fixed.
Kills with the Tactical Knife do not count towards the Veteran challenge for the gun, only kills by shooting will count towards the challenge. However, kills with the Tactical Knife do count towards the Marksman challenge for the weapon.
In general, most guns equipped with the Tactical Knife are held farther away from the player. This causes iron sights to appear smaller, but does not change weapon zoom in any way.
While aiming with the Tactical Knife equipped, the sights can be seen shaking slightly. This is most easily seen if the Tactical Knife combined with the Reflex Sight. Although this may hinder aiming, it adds no weapon sway or accuracy reduction.
The camouflage on the player's Combat Knife will be the same as the Tactical Knife.
Getting a kill with the tactical knife will count towards a bloodthirsty for Skulls Camouflage, however, if a normal knife is used, it will not count.