Its likely that they'll either get a new quest for relic weapons (Ala FFXI and "Relics" / "Mythics") and won't be on Zodiac weapons but will be on the new ones... or they'll create Zodiac Weapons for them. If they do create Zodiac Weapons for them, its likely the name will come from a weapon within Final Fantasy Tactics universe.

With that in mind, Valhalla is the likely name, as it is the "Legendary Fell Sword" from Final Fantasy Tactics. Arondight, Balmung, and Chaos/Deathbringer are the other Fell blades of that, but I do believe the final version will be Valhalla.