Assassin’s Creed Odyssey gives the protagonist Leonidas’s spear as a signature weapon throughout the main story.
The spear originally belonged to King Leonidas I of Sparta, who is shown at the beginning of the game during the Battle of Thermopylae. The player later controls either Alexios or Kassandra, and the chosen protagonist inherits the broken spear and uses it as an important part of their equipment and abilities.
The weapon is not merely a conventional spear. In the game’s fiction, it contains Isu power and can be upgraded as the protagonist advances. Its fragments and abilities help connect the Greek adventure to the wider precursor-civilization mythology of Assassin’s Creed.
The Sword of Eden and Apple of Eden are different Pieces of Eden found elsewhere in the franchise. Mjölnir belongs to Norse mythology and is associated with Assassin’s Creed Valhalla’s equipment, not Odyssey’s central weapon.