Most mainline Final Fantasy games call it Longinus, with some calling it Lance of Longinus. A true direct translation (ロンギヌス) is also Longinus.
I'm not really sold on the Holy Lance localization. I don't think it's fare to assume the creators made a mistake and meant the actual
Holy Lance. After all, Longinus is a Saint, he has notoriety outside the spear he used. https://en.wikipedia.org/wiki/Saint_Longinus
I can see a blacksmith naming a spear to honor Saint Longinus.EDIT:
Apparently Bravely Second: End Layer
has Longinus as a weapon, with this description.
The fateful spear used in the execution of a legendary prophet. He was the savior of his people, but was eventually taken prisoner by the land's rulers, who feared his influence. It is said to be a holy relic because it was bathed in his blood. It is particularly effective against creature of the sea.
This basically makes it the Holy Lance. However, it's not a Final Fantasy game.
Final Fantasy Tactics has a this weapon (only translated as Lance of Longibunne) with this description,
Many adventurers have lost their lives pursuing this spear, said to be capable of piercing solid stone. Legend holds it once slew a demon that had seized control of the mortal realm.
Which doesn't fit the description of the Holy Lance.EDIT2:
Okay, so the PSP version of Final Fantasy II has this description for Longinus,
An ancient weapon that pierced the side of an immortal.
I can now see the Holy Lance localization being valid.