The Combat Knife is a small blade weapon used for close quarters combat. Every major human army in the Metal Slug series uses knives.
The knife is the melee weapon of Marco, Tarma, Trevor, and Ralf, although Trevor will use kicks while on the ground and Ralf can also use Vulcan Punches. As with all normal melee weapons, it can kill nearly all human enemies in one strike, and can even hit multiple targets, but is useless against armored vehicles. Enemies such as Zombies, aliens, and bosses often take more than one melee strike to kill, but a melee attack does more damage than a pistol shot. The knife, like other close-range attacks, score more points per enemy than firearms and explosives.
Most human enemies, especially Fanatics, will also use knives when close to the player, but they take nearly a full second to attack, giving a vigilant player enough time to kill them or jump away.
In Metal slug 6 and 7 there exists a special weapon called the Zantetsu Sword, which upgrades your melee weapon attack with large waves of energy powerful enough to destroy armored vehicles and even bullets.
In Metal slug 3, swimming characters will use a strange, fan-like object instead of the knife.
|Standard||Handgun (Murder .50AE | Murder Model-1915 .38 Mk.1Am) | AR-10 | M-3685 | M60|
|Limited|| Heavy Machine Gun | Rocket Launcher | Flame Shot | Shotgun | Laser Gun | Iron Lizard | Super Grenade | Enemy Chaser | Drop Shot | Two Machine Guns | Zantetsu Sword | Thunder Shot|
|Bombs||Grenade | Fire Bomb | Stone | Earring Bomb | Smoke Bomb | Monolith | Snowball|
|Melee||Knife | Tonfa | Hatchet | Tomahawk | Punching Glove | Stun Gun | Wrench | Vulcan Punch | Argentine Backbreaker | Moon Slasher|
|Other||AA Machine Gun | Thunder Cloud | Mobile Satellite|