During his tenure as an Inquisitor serving the Galactic Empire, the individual known as the Sixth Brother wielded a distinctive spinning lightsaber with two blades. The destruction of this weapon, and consequently the death of the Sixth Brother, occurred a little over a year after the Empire's establishment. This event transpired on the Outer Rim moon of Raada, during a confrontation between the Inquisitor and the former Jedi Padawan Ahsoka Tano. Following this encounter, Tano recovered the kyber crystals from the destroyed lightsaber. After purging the taint imposed by the dark side, she integrated these crystals into her own newly-constructed pair of lightsabers.
The design of the Sixth Brother's lightsaber drew inspiration from that of the Grand Inquisitor's. While exhibiting some differences, such as the absence of the two spikes around the emitter, it did feature protrusions around the handle guard in both crescent and disc modes.
A unique aspect distinguishing it from other Inquisitor lightsabers was its capacity to function as a split saber. It could disconnect at the hilt, allowing the user to employ two lightsabers instead of a single, double-bladed weapon.
The power source for this weapon consisted of two kyber crystals, which had been forcefully corrupted to the dark side of the Force via a process known as bleeding. Ahsoka Tano surmised that these crystals were plundered from the Jedi Temple in the aftermath of the Great Jedi Purge.
The Sixth Brother received training in the use of this lightsaber, along with his fellow Inquisitors, at The Works located on Coruscant. His instructors included the Grand Inquisitor and, subsequently, Darth Vader.
In 18 BBY, the Sixth Brother journeyed to the remote moon of Raada in response to reports indicating Jedi activity. During his investigation, the Inquisitor located a group of rebels concealed within caves near the moon's only settlement. He utilized his lightsaber to kill the majority of them, sparing only the sisters Kaeden and Miara Larte. Kaeden was taken as a hostage to lure the mysterious Force-user back to Raada, while Miara was rendered unconscious prior to the battle to ensure her safety.
The capture of Kaeden did indeed entice her Force-sensitive friend, the former Jedi Padawan Ahsoka Tano, to return to Raada. However, Tano had secured allies in the form of Senator Bail Organa and his rebel faction, enabling her to orchestrate the evacuation of the moon's inhabitants. As the evacuation commenced, Tano confronted the Inquisitor without a weapon. The Sixth Brother, caught off guard and underestimating her abilities, was defeated when Tano, sensing the kyber crystals within the Inquisitor's lightsaber calling to her, used the Force to cause the weapon to explode, resulting in the Sixth Brother's demise. Tano recovered the crystals and their specialized mountings from the wreckage of the lightsaber, and respectfully closed the visor of the Sixth Brother's helmet over his face. Subsequently, she purified the crystals of the dark side's influence, before completing the construction of a pair of white-bladed lightsabers, some of whose parts came from the Sixth Brother's lightsaber, which she immediately used against the Imperial forces on Raada.
The Sixth Brother's lightsaber made its debut appearance in the novel titled Ahsoka. Its first visual depiction occurred in the sixth issue of the comic book series Star Wars: Darth Vader.