Kylo Ren's lightsaber

"Kylo Ren. [&hellip;] That's what his army called him. He was dressed in black, carried a "laser sword" like in the old Jedi stories."

- Eila, to Kazuda Xiono

Kylo Ren's lightsaber was a crossguard lightsaber constructed sometime before or during the year 34 ABY by Kylo Ren, Supreme Leader of the First Order and master of the Knights of Ren. The lightsaber, based on an ancient design dating back to the Great Scourge of Malachor, contained a cracked Kyber crystal, requiring it to have lateral vents on either side of the handle in order to divert the extra heat generated by the crystal.

During the cold war, Ren used the lightsaber to strike down Lor San Tekka, a member of the Church of the Force. When his father, Han Solo beseeched him to leave the First Order, Ren ignited the crossguard lightsaber through Solo's torso in an act of patricide. He later dueled the former stormtrooper known as Finn, and the Force-sensitive scavenger Rey, though he lost to the latter.

After recovering from his defeat on Starkiller Base, Ren assassinated his dark side master, Supreme Leader Snoke, and fought alongside Rey against the Elite Praetorian Guard. He killed several guards using his crossguard lightsaber before taking control of the First Order as Snoke's successor. On Crait, he was confronted by his uncle and former mentor, Jedi Master Luke Skywalker, and attempted to strike him down in battle. However, Ren's lightsaber was ineffective against his opponent as Skywalker had only projected his appearance on Crait whereas his physical form was still on Ahch-To.

The next year, Kylo Ren continued to use his lightsaber until he faced Rey on the remains of the second Death Star on the ocean moon of Kef Bir. After being saved by Rey from dying at her hands, Ben Solo had a Force vision with his father Han, who insisted him to give up the dark side of the Force and reminded that he still loved him. Again Ben Solo and no longer Kylo Ren, Ben threw off Kylo's lightsaber towards the horizon where it disappeared into the depths of Kef Bir's oceans.

Description
Kylo Ren's crossguard lightsaber was modeled on weapons that were used in the Great Scourge of Malachor, an event that occurred millenia before the New Republic Era. Despite its ancient design, Ren's lightsaber contained modern components within it. The lightsaber was crudely assembled and its unstable condition was evidence of Ren's inexperience in constructing such a weapon. It was built around a dangerously flawed kyber crystal; therefore, the lightsaber relied on its lateral vents to prevent the cracked crystal from overloading. Its focusing crystal activators served to split the lightsaber's red-yellow plasma stream into three channels, creating the crossguard blades, or quillons, which appeared after the ignition of the main blade. The lateral vents, from which the quillons emerged, diverted the extra heat produced by the crystal to either side of the hilt, giving the crossguard lightsaber an unstable and serrated appearance. Though he was capable of repairing his lightsaber, Ren favored its unstable and volatile nature.

Construction
"I'm being torn apart. I want to be free of this pain. I know what I have to do but I don't know if I have the strength to do it. Will you help me?''" "''Yes. Anything."

- Kylo Ren and Han Solo

The master of the Knights of Ren, Kylo Ren wielded a crossguard lightsaber prior to his ascension as Supreme Leader of the First Order. Whereas he once used a standard lightsaber during his time as Jedi Master Luke Skywalker's Padawan, Ren's crossguard lightsaber was built sometime before or during the year 34 ABY. It would serve as his weapon throughout his time as the dark apprentice of Supreme Leader Snoke, as well as afterward as Snoke's successor.

Search for Skywalker
During the conflict between the First Order and the Resistance, the dark knight used his crossguard lightsaber to kill Lor San Tekka, a member of the Church of the Force. Ren later used his lightsaber aboard the Finalizer, in a rage-induced temper tantrum &mdash;regarding a report about Finn's involvement in BB-8's escape from Jakku, destroying a computer terminal.

During her time on Takodana, the Scavenger Rey discovered Luke Skywalker's old lightsaber, that once belonged to Ren's grandfather Anakin Skywalker, in Maz Kanata's castle, where she had a Force vision. During the vision, she saw Ren using his lightsaber to cut down a clan leader. Ren later used his lightsaber during the Battle of Takodana to deflect blaster bolts fired at him by Rey.

Ren used his lightsaber again during the Battle of Starkiller Base. First, on a interrogation chair, when he had another a rage-induced temper tantrum, after finding out that Rey had escaped custody.

He also used it on his own father, Han Solo. It later crossed blades with the Skywalker lightsaber. Although he defeated and injured the former stormtrooper Finn in a brief duel, he was in turn defeated by Rey, who successfully channeled the Force within herself to fight back, striking Ren's lightsaber and knocking it from his hand.

The Supremacy
Despite the weapon being damaged, Ren repaired the weapon, adding a sleeker black casing to it. While in the presence of Snoke's Elite Praetorian Guards, the lightsaber came into the possession of Rey, who summoned it from Ren's side in an attempt to fight Snoke and his bodyguards. In spite of her efforts, Rey was telekinetically disarmed by Snoke, who commanded his apprentice to kill the aspiring Jedi. Ren used the moment as an opportunity to assassinate Snoke by cutting him in half with the Skywalker lightsaber. Activating his own lightsaber, Kylo Ren fought alongside Rey against the Praetorians, all of whom perished while attempting to avenge their slain leader.

Crait
After the battle in Snoke's throne room, Ren assumed the title of Supreme Leader and brought the forces of the First Order to the planet Crait, where he attempted to fight his uncle Luke Skywalker, only to discover that he was fighting a Force projection of the Jedi Master. As a result, the Resistance was able to escape before Ren could destroy them.

Kef Bir
Following his defeat on Crait, Ren continued to wield the lightsaber as he worked to consolidate the First Order's power. Whispers of the return of the long dead Galactic Emperor and Sith Lord Darth Sidious incited Ren to locate the Emperor and eliminate the threat to his power. These same rumors inspired his Jedi rival Rey and her allies to do to same and the pair's concurrent quests and Force-bond brought them to the ocean moon of Kef Bir in the Endor system. Kef Bir was the site of the ruins of the second Death Star and the location of a Sith wayfinder that could lead the way to the Emperor's location.

On Kef Bir, they faced each other in a final confrontation, Ren bearing his lightsaber and Rey the repaired Skywalker lightsaber. He gained the upper hand and was prepared to strike her down, but as they dueled his dying mother Leia Organa reached out to him through the Force, distracting him from making the killing blow. Rey seized the opportunity and impaled Ren with his own weapon, but after sensing Organa's death, healed his grievous wound before departing. As Ren stood alone on the battle station after the duel, he was overcome by a memory of his deceased father Han Solo, who spoke to him and called to his son to change, much as he had in their fateful confrontation on Starkiller Base. Touched by the love of his mother and father and the compassion shown by Rey in healing him, Kylo Ren cast his lightsaber into the ocean and reclaimed his former identity as Ben Solo.

Behind the scenes
Kylo Ren's lightsaber first appeared in Star Wars canon in the 2015 film Star Wars: Episode VII The Force Awakens. The introduction of the lightsaber was well-publicized in the media, including on The Colbert Report and @Midnight on Comedy Central. The lightsaber was also the subject of a number of pieces of fan art released in the days after the films first teaser trailer premiered.

Non-canon appearances

 * Disney Infinity 3.0
 * LEGO Star Wars: The Force Awakens
 * LEGO Star Wars: The Skywalker Saga
 * Star Wars: Galaxy of Heroes