The Cyertsye Tyemnovo Sveta, or "Heart of Dark Light," was a massive longsword wielded by Jedi Master Aron Kellemann. It was resistant to lightsabers solely by virtue of its density and could be wielded only through a variation of Force Weapon, allowing the user to establish a grip on the weapon with the Force as well as a physical grip. Due to its mass, however, it was better suited to melee battles than duels.