Phantom Ganon's Sword, also known as the Beast's Blade, is an item from The Legend of Zelda: The Wind Waker. This sword is wielded by the ghostly entity Phantom Ganon. Like some weapons wielded by enemies in the game, Link can utilize the blade after Phantom Ganon has fallen. Inscribed on the sword's blade are the Hylian words "Zubora Gabora", likely a reference to the blacksmiths from The Legend of Zelda: Majora's Mask.
Within Ganon's Tower, there is an area called the Illusionary Room. In this area, Link must defeat Phantom Ganon multiple times to progress in the dungeon. Link can find his way through the maze by taking the door that the hilt of Phantom Ganon's Sword points to after being balanced on its point when Link defeats Phantom Ganon. In the last room of the maze, Link must take up the sword and attack a wall with a decorative pattern on it to exit the maze.
Phantom Ganon is depicted wielding two of these swords in Hyrule Warriors Legends. His wielding dual swords may be to make him more closely resemble his master Ganondorf, who wields two Great Swords in Hyrule Warriors as his main weapon moveset. Besides the swords use as weapons by Phantom Ganon, it also appears as Phantom Ganon's Gold Material drop.
In Wind Waker: Watchers of the Triforce, Phantom Ganon's Swords are left behind along with the Triforce of Power following Phantom Ganon's destruction.