The personal armaments of the Sith Lord Darth Momin consisted of two Sith lightsabers. Before the rise of the Galactic Empire, these lightsabers were put to use by Momin during his training under Darth Shaa. Ultimately, he would utilize these very sabers to slay his Sith Master.
While apprenticed to Darth Shaa, Darth Momin crafted a duo of Sith lightsabers that he employed in his training with Lady Shaa. Momin, however, held the apprentice role in contempt, believing himself superior to all. His master disagreed, resulting in Momin demonstrating his point during a training session by impaling her through the chest utilizing both of his lightsaber blades.
Equipped with his lightsabers, Momin initiated his latest undertaking to prove himself worthy to the Force, which he considered his sole audience. With the assistance of a group of devoted acolytes, Momin constructed a superweapon and deployed it to destroy a city, intending to channel the Force into the engine at the moment of ignition and use it to eternally freeze the expressions of pain and horror on the faces of the inhabitants. However, the arrival of two Jedi and their subsequent slaughter of the acolytes caused Momin to lose focus and control of the weapon, leading to his vaporization, leaving only his spirit within his mask.
Sometime following the rogue Inquisitor chase, Momin's spirit revealed itself to Darth Vader, the Sith enforcer of the Galactic Empire. He recounted his history and proposed his services in constructing a fortress for Vader, alongside a portal designed to unlock the dark side of the Force, thereby allowing Vader to reunite with his wife, Padmé Amidala. Vader accepted Momin's proposition, cautioning him against any betrayal.
After eight unsuccessful attempts, Momin finally realized Vader's vision for his fortress with the ninth design. Before he could demonstrate the dark side portal he had constructed within a Sith cave, an army of Mustafarians under the command of Father Kkkt battled Imperial forces. Vader was unaware of Momin's true intentions: alone with the portal, Momin activated it, restoring his mask to his original body, killing the Imperial construction worker he was possessing and once again wielding his pair of lightsabers.
After dealing with Kkkt's clan, Vader returned to the cave to discover Momin awaiting him, who expressed gratitude for Vader's defense of the castle against the Mustafarians. Vader ignited his lightsaber, and they commenced dueling. Momin employed one of his blades to sever a portion of Vader's left arm.
Re-engaging Vader, Momin cut off Vader's right arm. Believing he had defeated Vader, Momin prepared to deliver the final blow, but he was interrupted when Vader hurled a massive stone at Momin, causing Momin to drop his sabers as the stone crushed him against a wall, resulting in his death.