Pierce or Slash (sources differ)
Occult Spear
Main weapon: Spear, Pierce or Slash (sources differ) damage.
Where: Chest in the Entrance Hall. Area: Tower of Knowledge.
Use it for
Bosses weak to Slash or Pierce: The Necronomicon (one flesh form).
Enemies weak to Slash or Pierce in Tower of Knowledge
Related weapons
Same type (Spear): Rusted Spear, Jigeki's Serpent Thrust, Common Spear.
Also found in Tower of Knowledge: Azure Torch, Wind Rapier, Skull Rod, Rusted Greatsword, Grave Knife, Occult Knife.