A Knife, or known primarily as a Combat Knife or Fighting Knife is a cutting weapon designed for military use, specifically for close combat; however, since the end of trench warfare, most military knives have been primarily designed for utility/tool use (clearing foliage, chopping branches for cover, opening ammunition crates, etc.).
It should only be used in drastic close-quarters situations where the player runs out of ammo in both their primary weapon and pistol, or when sneaking up on an enemy. It can take one to four swipes to kill an opponent, depending on where the blows hit.
The Combat Knife is issued to the new factions and is replaced by the Bayonet for the Engineer kit's bolt-action rifle, which, when equipped, uses the aim button to thrust.
In Battlefield 1942: Secret Weapons of WWII, the Commando Knife and the German Elite Knife are new weapons issued to the Special Air Service and to the Waffen-SS respectively. They replace the standard combat knife from the base game for these factions. They act like a normal combat knife, except they can be thrown with the primary fire key, or used as a melee weapon with the secondary fire key. Each kit comes with five knives.
In Battlefield Vietnam, the Knife is issued to all American and South Vietnamese kits. Its appearance is drastically different from the 1942 version, being much larger, and held with the blade down and to the side, rather than upright. However, it does the same damage. The Axis knife was also redesigned, into the Machete.
In Battlefield Vietnam's official WWII mod, the Knife is issued to every kit. Like in Battlefield 1942, the knife's model varies between factions, with an Allied knife issued to the US Marines and an Axis knife issued to the Imperial Japanese Army. It uses the same models as those from the previous game, though uses very different animations. Its performance and stats are identical to those from its counterpart from the previous game.
In Battlefield 2, the Knife is issued to every kit, and can kill in a single hit. Unlike previous games, the combat knife's skin does not change between factions: there is a single game file related to the knife, which is used for all soldiers, rather than multiple for each faction.File:BF2 Knife Stab.ogg
In BF2:MC, a Combat Knife is issued to the Spec-Ops kit, and kills in one hit, much like other Battlefield games. USMC and EU soldiers will be issued with a Model 15 Combat Knife, while PLA kits will have a Type 95 Combat Knife, and MEC kits will have the Kukri. Although they differ in appearance, they all perform similarly.
The BJ-12 Combat Knife is issued to every kit. It kills with a single hit, and a kill will award the player with the victim's dogtag.
After fifty kills with the knife, the player earns the Dogtag Dagger, a knife replacement with a dogtag attached to the handle. Aside from aesthetics, it does nothing for gameplay.
The Kniv-1 combat knife is available for use for every type of kit, and can be used to attack enemies to claim their Dog Tag and break open wooden doors and fences. A hit will result in an assured one hit kill. However, it will probably take about 2 hits to kill friendlies.
When pulling out the knife, it will automatically do a first attack. A player can quickly hit the knife button again and there will be two fast swipes which can help in a first close-quarters strike, but only when the player pulls out the Kniv-1.
In Battlefield Heroes members of the Commando Class have the option to use a combat knife as a weapon.
The knife used in Battlefield Heroes begins a trend of knives inflicting splash-like damage, spread in an area in front of the wielder, rather than bullet-like damage fixed on the crosshair.
— In-game description
In Battlefield: Bad Company 2's singleplayer, the knife is the first usable weapon in the game, and can be equipped upon three occasions. The first time is after the opening cutscene of Operation Aurora where the player loses their Thompson, the player pulls out the knife and kills a Japanese guard with it. Soon after, the player receives a Type 100 and the combat knife can no longer be equipped as a stand-alone. The second time is at the beginning of the mission Upriver, when the player must use the combat knife to quietly take out a sentry at an outpost overlooking a Bolivian Militia base without raising the alarm. The third time it is used is in the beginning of Airborne, where the player is equipped with a combat knife again, this time in order to kill a Russian soldier. The player immediately picks up the soldier's AKS-74U, however, and can no longer equip the knife as a standalone weapon. Throughout most of the campaign, the player can only use the knife in an attack sequence.
In multiplayer, the Combat Knife is the standard melee weapon, usable by all kits. It will kill an enemy player in a single strike. It is not a feasible stealth weapon, however. If the player misses their target, a slashing sound (and possibly a verbal que from the character) may alert them. If the player does hit their target, the victim may choke or make another noise that alerts surrounding players. The knife is also a useful tool for knocking away certain destructible barriers, such as windows, fences, barbed wire, wooden doors, wooden railings, and many other light physical barriers in the player's path. Using the knife to knock away barriers provides the player with a way to move around more freely without wasting ammunition. When using the knife on an enemy within its range, roughly five feet, it will cause the player to lunge forward against the enemy and perform a stabbing attack. An attack without an enemy target will instead cause the player to slash with the knife. The slash attack is still capable of killing an enemy if the strike connects. Although the lunge makes knife kills more likely, it is still possible for the target to evade the swing by moving away from the attacker. The knife will kill should the victim be close enough, even if the knife would not actually hit him.
When players knife an enemy player in Battlefield: Bad Company 2, they receive an award called a dogtag. These appear as bronze, silver or golden dogtags, depending on the victim's rank, with their name written below them. There are also several awards related to knife kills which the player can acquire. The dogtags from all of a player's past victims can be viewed in the Main Menu, providing a running tally of how many individual dogtags players have acquired as well as player-specific ones.Players can kill certain enemies in vehicles, if they are in an exposed position, such as the Quad Bike, both of the boats featured in the game, or a gunner in a light vehicle.
— Battlelog description
In Battlefield 3, the Knife is a melee weapon. Unlike in previous titles, there are different ways to use the combat knife. The weapon can also be used in all three modes in the game (singleplayer, co-op, and multiplayer).
— A loading screen tip regarding Knife Takedown
Holding the attack button and approaching an enemy from behind will perform a fatal Takedown attack. Knife takedowns can only be performed when behind or to the side of an enemy, however you may be able to do a special front takedown if your enemy turns right before you start the animation. There are 12 knife animations in all, 4 for each stance, from the back, from the right, from the left, and a rare animation in which you stab the enemy while they're turning towards you. When a takedown is performed, the knife user is awarded the victim's Dogtags. This is the only way to obtain them.
When knifing an enemy, you do not appear on the radar. However, knife sound effects may betray your position, as well as a team that communicates who may sound the alarm that there is a enemy soldier with a knife behind the team. There is no counter to the knife, though people can be killed while knifing, and sometimes lag may cause your bullets to kill the person knifing you mid-animation.
The knife has a special feature - if there is no target, or the target is not in range, then the knife points horizontally when equipped. However when the target becomes in range the knife often moves to a vertical position to indicate that the target is within range.
Quick knife often only removes 33% - 50% health with a shorter range and has the same time delay between stabs, so it is often faster to equip the knife, "slash" an enemy, and kill them. With the 1.04 Version patch, knifing speed has been increased. If a player is not directly above an enemy in prone position, the will automatically "quick knife" them. On the PS3 and 360 versions, the Quick melee attack and the wieldable knife are bound to the same button, so tapping the button will execute a quick slash and then return to the previous weapon or equipment, while holding down the button will execute the slash and keep the knife held out. PC players can choose whether to bind the functions separately or together. Quick knifing can destroy objects such as chain link fences with a single blow.
- In Battlefield Vietnam, the files for the ARVN and U.S. knives are the same as those used by the allies' knife in Battlefield 1942, with a different model. The axis combat knife still exists in the game files, but goes unused, replaced by the NVA and Viet Cong melee weapons.
- In Battlefield: Bad Company it is possible to cut down small trees with the knife.
- Battlefield: Bad Company 2 is the first Battlefield game where the player is not allowed to wield the knife as a weapon, it now functions more as a melee attack than a CQC weapon. The player just uses the knife then puts it away instantly, returning back to wielding the previously equipped item. The only exceptions of this are the beginnings of Operation Aurora and Airborne.
- A glitch can occur in Bad Company 2 when the player is climbing a ladder. If the player starts climbing in mid-slash, they will equip the knife after reaching the top.
- An update for Bad Company 2 reduced the lunge distance for the combat knife.
- Occasionally, after slashing with the knife, the player character may hold their knife for a few seconds the same way as in the mission Operation: Aurora, usually during a small lag spike.
- In Battlefield 3, when the knife is equipped, it will be raised into a stabbing position when the player is able to perform a stealth takedown.
- In Battlefield 3, a glitch may occur where the player, if he's using the knife after a backstab takedown, when running, will be raised even if no enemies are available for stabbing.
- In Battlefield 3 Blackburn's and Dima's knifes are different cosmetically.
[[Video:BFV knifing|thumb|left|300px|Knife combat in Battlefield Vietnam, on the map Operation Flaming Dart.]] thumb|right|300px|Gameplay with the Combat Knife in Battlefield: Bad Company 2's multiplayerthumb|right|300px|Different knife takedown animations in Battlefield 3.