The gunblade, as it is known, is a family of sword weapons from Final Fantasy VIII, a Squaresoft roleplaying game for Playstation and PC. The weapon consists of a large blade whose hilt contains a small revolver pistol. The pistol's short barrel runs along the middle of a blade (it is unclear from the images whether the pistol contains one or two barrels). During combat, if the player taps the R1 trigger on the gamepad at the very moment that the gunblade wielder strikes, there is an explosion, and the target takes greater damage than usual. It was introduced into game-play as a way of adding an extra element of technique to the battle system.
Since the gunblades in the game are never used as a projectile, ranged weapon, there is no formal explanation of what the purpose of the pistol is, but there are several theories that have been tossed around. The first is that the gun does not actually shoot a projectile, but each bullet is a small explosive that is triggered while inside the victim, exploding along the edge of the blade, and thus damaging the victim from the inside. The second and more common theory is that the pistol does shoot a normal bullet, but that it is most effective at close range, while striking, possibly because the presence of the blade greatly reduces the accuracy of firing at longer ranges.
Similar Historical Weapons
The gunblade has historical origins as well. There are several documented cases of flintlock pistols that were built into a large bayonet, usually a large dagger or a small saber or cutlass. This would enable the carrier to fire a shot, but then still have a weapon in hand during heavy fighting since reloading time could be quite long and dangerous while in close combat. The difference between these historical weapons and the gunblade of Final Fantasy VIII is simply its usage: the sword and pistol of the gunblade are meant to be used in tandem, while historical pistol/sword combos simply attached two weapons together for convenience. Today, the same basic principle lives on in the usage of the bayonet. Although fixed bayonetted rifles were once common practice, the current practice is the usage of removable bayonets, which places them slightly farther away from the gunblade design of Final Fantasy VIII.
In the game, there are seven different gunblades that the main character, Squall, can equip and one gunblade that his rival, Seifer (who you can control at one point in the game) uses. Here are the seven different types of gunblades Squall can equip and which in-game objects are required to make them. The names and descriptions are taken from menus within Final Fantasy VIII:
Revolver: Squall's basic weapon. The gunblade's original model is the Revolver. It lacks in power, it more than makes up for its reliability.
M-Stone Piece x6; Screw x2
Shear Trigger: An improvement in power over the Revolver, Shear Trigger uses the same blade as the Revolver, but the gun aspect is now more powerful.
Steel Pipe x1; Screw x4
Cutting Trigger: The Cutting Trigger is the latest model of gunblade, made by replacing the blade of the Revolver with the powerful Cutting Sword.
Mesmerize Blade x2; Screw x8
Flame Saber: The Flame Saber got its name from its red blade. This gunblade is very similar to the Shear Trigger. The only difference is that it has the Cutting Trigger's handle.
Betrayal Sword x1; Turtle Shell x1; Screw x4
Twin Lance: The Twin Lance is a gunblade forged with two blades. The two blades work synergistically to inflict severe damage. The only drawback is its heavy weight.
Dino Bone x1; Red Fang x1; Screw x12
Punishment: The Punishment looks almost identical to the Twin Lance, but it is lighter and more powerful. The only gunblade more powerful than this is the Lion Heart.
Chef's Knife x1; Star Fragment x2; Turtle Shell x1; Screw x8
Lion Heart: Of all gunblades, the finest model is Lion Heart. It requires rare items to be remodeled to its highest quality.
Adamantine x1; Dragon Fang x4; Pulse Ammo x12
Here are three links describing and picturing replicas of historical pistol/sword combo weapons: