In Assassin's Creed Odyssey, which legendary weapon grants the protagonist immortality?

In Assassin's Creed Odyssey, the Staff of Hermes Trismegistus grants the protagonist immortality. The staff is an Isu artifact entrusted to Kassandra, or to Alexios if that character is chosen, and it becomes central to the game's modern-day and ancient storylines.

The staff's power prevents its bearer from aging normally, allowing the protagonist to survive for centuries. Its significance is revealed through the character Layla Hassan, who encounters the long-lived protagonist in the modern era. The artifact therefore links the Greek historical narrative with the series' science-fiction mythology.

The Spear of Leonidas is an important weapon used early in the game, but it does not provide immortality. Apples of Eden and other Pieces of Eden also have extraordinary abilities, yet they are distinct artifacts. The staff is specifically associated with Hermes Trismegistus and prolonged life.