Moonveil: the ruin roof by the Academy, do not drop into the swamp

The katana is at the Academy of Raya Lucaria, in a chest on the roof of the ruins. From the marionette statue, go up the rubble, not down into the muck. Half the map wastes a trip down there.

At +20 it scales off intelligence. Transient Moonlight is fine for PvE.

If the chest is empty, you already took it. A second one does not respawn.