Immortal Slaying Scythe, Harpe (不死身殺しの鎌・ハルペー, Harupei?), the snake hunter's scythe (蛇狩りの鎌, ?), is a divine sword from Greek mythology used by Perseus to kill the Gorgon Medusa and one of the many weapons inside Gilgamesh's Gate of Babylon. It is described as a monster-killing holy sword with a special shape similar to a scythe, having the cutting edge on the inside of the blade, though it isn't actually an outstanding sword by itself. Its true strength is its trait of Refraction of Longevity (屈折延命, Kussetsu Enmei?), which is a divine ability that nullifies the "undying attribute" of immortals and inflicts wounds that cannot be restored by any methods other than healing in accordance to the natural laws. It is one of five Noble Phantasms given to Perseus, the most legendary artifacts given to a single person in Greek history, for his quest to slay Medusa. It was given by Hermes, and as it was returned to him once the task was completed, it can be called an “Anti-Medusa” weapon.
 Fate/complete material II: Character material - Weapons: Harpe, p.135 English | JapaneseUser: Gilgamesh
A divine sword from Greek mythology. One of the Noble Phantasms owned by Gilgamesh. It has a special shape similar to a scythe, with the cutting edge on the inside of the blade. It also has the power to negate the “undying” attribute. The hero Perseus received the sword from Hermes, so that he could exterminate the snake-haired witch Medusa. The legend goes that Perseus approached Medusa – who would turn everybody that looked at her into stone – by using a mirrored shield, and then cut off her head with Harpe while she slept. Because Perseus returned Harpe to Hermes once the task was completed, it can be considered an “Anti-Medusa” weapon.