Legendary Weapons are weapons found in Spectrobes: Origins. They are a special type of weapon infused with the power of an Evolved form Spectrobe. A Legendary Weapon can be one of the six different types of weapons in the game.
The Legendary Weapons were sealed away by Spectrobe Masters long ago. They can be found all across the Kaio system, sealed within Stone Markers. Obtaining the weapon found on the Stone Marker requires the Cosmokey.