Double-bladed weapon

Double-Bladed Weapons, also called Thief Swords, are a type of recurring weapons in the Final Fantasy series. They are unique weapons, in that they bear two independently separate blades the tip of each ends and they have their own method of functionality. This sort of weapon, like the Gunblade, sees its use in the hands of both playable characters and NPCs of the series.

Final Fantasy V
The Twin Lance is the first double bladed weapon, appearing as a boomerang type weapon and can be equipped by Freelancers, Thieves, Ninjas and Mimes. With its double blades, this weapon can attack twice in one turn.

Final Fantasy IX
Thief Swords are a series of weapons unique to Zidane Tribal.

List of Final Fantasy IX Thief Swords:
 * Butterfly Sword
 * The Ogre
 * Exploda
 * Rune Tooth
 * Angel Bless
 * Sargatanas
 * Masamune
 * The Tower
 * Ultima Weapon

Final Fantasy XII
Judge Magisters are known to wield paired weapons, one short, and one long; separate, these weapons act like single hand weapons, conjoined, they act akin to a double ended polearm, with both blade's edges facing outwards rather than a cyclical parallel. One prime example is of Judge Gabranth, whose weaponry comprises of the Chaos Blade and the Highway Star.

They also feature weapons other than blades, such as Judge Drace's dual maces.

Final Fantasy XIII
Oerba Yun Fang wields spears bearing two spearheads. In addition, this weapon can also be converted into a sansetsukon-nunchaku form. Zatetsuken is also a dual-bladed weapon.

List of Spears:
 * Bladed Lance
 * Glaive
 * Kain's Lance
 * Dragoon Lance
 * Dragonhorn
 * Kain's Lance
 * Partisan
 * Rhomphaia
 * Shamanic Spear
 * Heretic's Halberd
 * Punisher
 * Banescissor Spear
 * Pandoran Spear
 * Calamity Spear
 * Taming Pole
 * Venus Gospel
 * Gae Bolg
 * Gungnir

Lightning Returns: Final Fantasy XIII
Dual-blades are a weapon type available to Lightning. They lower Lightning's overall strength while providing the passive ability Precise HP Restore. While equipped with dual-blades, Lightning hits twice per attack.

List of Great Swords:
 * Double Saber
 * Black Gantry
 * Godly Gambrel
 * Tower Blade
 * Heaven's Bridge
 * Gagnrad
 * Double Deity
 * Guard Stick
 * Crocea Mors

Dissidia Final Fantasy
Zidane wields a pair of Mage Mashers which combine into the Ogre and Gabranth wields the Chaos Blade and Highway Star.

Dissidia 012 Final Fantasy
Zidane and Gabranth return wielding their signature weapons. Lightning wields Odin's Zantetsuken while executing HP moves.