A Chainsword is a common form of chain weapon, essentially a sword with motorized teeth that run along the blade like those of a chainsaw. Most versions make use of monomolecular-edged or otherwise razor sharp teeth. The weapon makes an angry buzzing sound as the teeth spin around, intensifying into a high pitched scream as they grind into armour.
It is a popular weapon of Imperial Guard officers, and boarding and assault parties - such as Space Marine Assault Squads, Chaos Space Marines - especially Raptors - Eldar Striking Scorpions, and Pirates.
