Turai's Sword is a weapon given by Durmand [Historian], for the Bonus Mission Pack Mission The Battle of Jahai. It is automatically customized for the character that received it, and must be equipped in order to proceed with The Battle of Jahai.
Dye affects the real sword's grip, but not its inventory icon's grip.
Bug! The attack animation of the sword, the air draft from the swing of the sword seems to be perpendicular to the sword. (i.e., if you swing the blade horizontal, the wind animation goes in a vertical motion. See image on right.) This animation matches the way Turai Ossa himself uses the sword in The Battle of Jahai mission.