The Lightsword of Lord Corvax was an age-old lightsaber once held by Lord Dorwin Corvax, who was married to Lady Corvax.
Following Dorwin's demise, Lady Corvax attempted to bring him back to life. She used the Bright Star to power the Aeon Engine in this endeavor. This effort only partially succeeded, leaving Dorwin stuck between the realms of the living and the dead. After this, Dorwin became known as the Black Bishop, and the planet Mustafar underwent a drastic transformation from a lush world to a desolate landscape of lava. Lady Corvax concealed the Lightsword within her Sanctum.
Decades later, during the Imperial Era, the Black Bishop eventually passed the Lightsword on to one of his descendants. This new wielder employed it to lead an army of archaic droids called the Marching Horde, engage in a duel with Darth Vader, and ultimately destroy both the Bright Star and the Aeon Engine. The destruction of these devices damaged the Lightsword, rendering it incapable of projecting a blade. Aboard the descendant's ship, the Windfall, the descendant and ZO-E3 discovered that the Lightsword, when combined with a recovered artifact, projected a star map leading from Mustafar to a location somewhere in Wild Space.
The Lightsword possessed traits that made it quite distinct among lightsabers. While it had a single blade, like most of its kind, it also featured a crossguard. However, unlike the crossguard lightsabers such as the one wielded by Kylo Ren, this crossguard lacked vents or smaller blades, instead showcasing a semicircular design. It resembled a conventional sword's crossguard to a greater degree.
Furthermore, in contrast to the majority of lightsabers, its Kyber crystal (the power source of the blade) was exposed rather than being hidden within the hilt. The crystal was located in the center of the crossguard and emitted a blade through two curved prongs that spiraled from the top of the guard. The crystal itself exhibited a very dark blue color, and it sparked with electricity upon activation, resulting in the formation of a blue blade. The lightsaber's hilt released smoke briefly after the blade was deactivated. The blade also had a limited duration, automatically shutting off after a specific period.
The hilt was slender, terminating in a flat, circular pommel adorned with golden accents. These accents were also present on the crossguard. The entire lightsaber was constructed from a grey metal. Given its representation of the power wielded by Lady Corvax and her husband, ancient Mustafarian technology was programmed to respond to it. It could command the Marching Horde through particular gestures performed with the ignited blade, it could be presented to sealed doors to trigger their opening, and it functioned as the key to the chamber where the Bright Star was hidden.