The legendary sword wielded by King Arthur in Assassin's Creed Valhalla is Excalibur.
Valhalla includes Excalibur as a secret greatsword that Eivor can obtain by collecting tablets and reaching a hidden location in England. The weapon is presented through the game's blend of Viking history, British legend, and Assassin's Creed mythology. Its inclusion treats Arthurian material as part of the world's legendary and semi-historical traditions rather than as a straightforward biography of King Arthur.
The sword is one of several special weapons and myth-inspired rewards available in Valhalla. Finding it requires exploration and solving environmental challenges, so it is not simply awarded through the main story. Its unusual appearance and powerful ability make it a popular discovery among players.
Excalibur should not be confused with Caladbolg, a different legendary sword associated with Assassin's Creed Origins, or with the Isu weapons that appear elsewhere in the franchise. Valhalla's central protagonist is Eivor, but Excalibur itself belongs to Arthurian legend.