Zero's Lament is a weapon that can be obtained in Lunar Shadow.
If the player takes the Lunar Sickle instead, Zero's Lament can be found in the Myst Zone instead, by solving a puzzle in Servant Quarters RR and entering one of the doorways that are created by the puzzle.
Zero's Lament literally does nothing.
ZERO'S LAMENT: a worthless weapon that
was meant to do something. However, its
creator was an useless fool and failed.
- Zero's Lament uses weapon ID 8, represented by a green block.
- Considering that the weapon literally does nothing, it's either a joke weapon or a test weapon.