The Skywalker saga is divided into three: the original trilogy, the prequels, and the sequel trilogy.
The original trilogy introduced the audience to the characters that were going to lead this saga for years, along with the events that would mark the path for the rest of the movies. The prequels focused on the backstory of Anakin Skywalker, from his days as a young slave in Tatooine to his rise as Sith Lord Darth Vader. The sequels brought the arcs of the main characters from the original trilogy to an end and introduced a new generation of heroes and villains, and with them came new events, concepts, and objects as well, as the new characters needed their own stuff to stand out from the rest. Among those were Kylo Ren (Adam Driver) and his lightsaber, which was unlike any other in the Skywalker saga as it was a crossguard one, which caused a big impression since its debut.
The crossguard lightsaber was first seen in the teaser for Star Wars: The Rise of Skywalker. The lightsaber was originally the one he used as Ben Solo while training under his uncle, Luke Skywalker, and it had a blue blade, but after his turn to the dark side, he modified it and incorporated a crossguard hilt. The lightsaber contained a cracked Kyber crystal that gave it its red tint, and because it was cracked, the weapon required lateral vents on either side of the handle to divert the extra heat.
Although an exact reason for Kylo Ren to choose a crossguard lightsaber hasn’t been revealed in either movies or extended (canon) media, and aside from it being safer due to the cracked crystal, it most likely has to do with the history behind the design. While the crossguard lightsaber first appeared in The Force Awakens, within the Star Wars universe it goes a long way back. According to other canon sources, the crossguard lightsaber was common among Makashi (a form of lightsaber combat) practitioners, and among its most notable wielders, way before Kylo Ren’s time, was Darth Atrius, who used two of these imbued with his anger. During the High Republic Era, Jedi Master Stellan Gios wielded one with an additional folding physical crossguard that ed the blades from the vents. Ezra Bridger found an ancient green-bladed crossguard lightsaber on Malachor during the Galactic Civil War, but it broke when he activated it.
The one that could have influenced Kylo Ren’s decision to build his own crossguard lightsaber is Darth Atrius’. This Sith Lord lived during the time when the Sith were a dominating force in the galaxy, and his crossguard lightsabers were especially powerful as they had the ability to bring out the inner rage of the bearer, leading them into a killing frenzy, which is why they were ultimately destroyed. The reason for Kylo Ren to use a crossguard lightsaber instead of a traditional one in the Star Wars sequels, then, can go two ways: either he took inspiration from Darth Atrius’ and his extremely powerful and dangerous weapons, or he chose this design as it allowed him to operate safely without losing the power of the crystal.
