Kassandra uses a spear as her signature weapon in Assassin's Creed Odyssey.
The weapon is the broken Spear of Leonidas, an Isu artifact passed down through Kassandra's family. It is not simply a normal battlefield spear: its connection to Leonidas and the First Civilization gives it an important role in the game's story and abilities. Kassandra uses it throughout her journey across the Greek world.
Assassin's Creed Odyssey allows the player to choose Kassandra or Alexios as the playable Eagle Bearer. The game's canonical protagonist is Kassandra, although both characters can be selected by the player. The spear remains central to the chosen character's combat and progression, so the weapon's identity is distinct from the traditional hidden blade.
Odyssey includes swords, heavy blades, bows, and other equipment that can be changed or upgraded. Those weapons are ordinary gear categories, whereas the Spear of Leonidas is a named story artifact. This distinction makes “a spear” the precise answer rather than a generic weapon such as a sword.