Gae Bolg

Gae Bolg is a polearm from Final Fantasy XIV. When used by Noctis to deliver a warp-attack, the attack inflicts +44% damage onto the target.

Source
Gae Bolg can be obtained as a special DLC through the Road Trip promotion.

Trivia

 * Gae Bolg is an Irish term that translates variously into "spear of mortal pain/death", "gapped/notched spear", and "belly spear." In Irish mythos, it is a specialized spear that belongs to a hero named Cúchulainn. It is crafted from the bone of a sea monster named Coinchenn.
 * Perhaps only by coincidence, this same Irish hero has a berserker-like battle ability called riastrad, which has been variously translated as "warp spasm." However, besides its similar name, it bears next to no resemblance to Noctis' warp-strike ability.