Kylo Ren's lightsaber

Kylo Ren's lightsaber was a crossguard lightsaber constructed and utilized by Kylo Ren approximately thirty years after the Battle of Endor. The lightsaber was crudely assembled based on an ancient design dating back thousands of years to the Great Scourge of Malachor. A single cracked Kyber crystal, barely able to contain the weapon's power, necessitated the lateral vents which diverted the extra heat produced by the crystal to either side of the hilt, and gave the weapon's red plasma blades an unstable, serrated appearance. Kylo wielded this weapon while working alongside the Knights of Ren and the First Order. The lightsaber was used to murder Church of the Force member Lor San Tekka, and Ren's own father, and later crossed blades with the lightsaber that formerly belonged to the Skywalkers; Ren defeated and injured the former stormtrooper known as Finn in the duel, but was overpowered in the ensuing duel with Rey. Rey successfully channeled the Force within herself to fight back, striking Ren's lightsaber and knocking it from his hand.

Behind the scenes
Kylo Ren's lightsaber was introduced in the first teaser trailer for Star Wars: Episode VII The Force Awakens. The trailer, released on November 28, 2014, showed Ren walking through a snowy forest on Starkiller Base and igniting the lightsaber. The introduction of the lightsaber was well-publicized in the media, including on The Colbert Report and @Midnight on Comedy Central. This earned it the name of "The Jesus Saber" due to its similarity to a Cross. The lightsaber was also the subject of a number of pieces of fan art released in the days after the trailer premiered.

It appeared twice in the second trailer that debuted at Celebration Anaheim 2015. The trailer showed Ren swinging the lightsaber, and later holding it in his left hand while he holds out his right. The concept of a crossguard lightsaber was first introduced in Star Wars Legends, previously known as the Expanded Universe. The lightsaber, which had two beams rather than three, made its first appearance in the 2004 comic book Star Wars: Republic 61: Dead Ends.

Appearances

 * Star Wars: Episode VII The Force Awakens
 * Star Wars: The Force Awakens novel
 * Star Wars: The Force Awakens: A Junior Novel
 * The Force Awakens: Rey's Story

Non-canon appearances

 * Disney Infinity 3.0
 * LEGO Star Wars: The Force Awakens