The Truth Seeker is Y'shtola's signature weapon in Final Fantasy XIV starting from the Heavensward expansion to the end of the Stormblood Expansion. It is comissioned by Tataru Taru through the Conjurer's Guild in anticipation of Y'shtola's return to the Scions, and is handed to her after awakening from her sojourn in the Lifestream.
The Truth Seeker is one of Y'shtola's unlockable weapons. It can be obtained either by random chance when redeeming a Treasure token, or by purchasing them from the Shop for 7,200 Gil. Like all other characters' weapons, having it equipped carries no advantages or disadvantages.