Anakin Skywalker carried this blue-bladed Jedi weapon throughout the Clone Wars. After dueling his former apprentice on Mustafar, Obi-Wan Kenobi took Anakin's lightsaber and kept it on Tatooine for nearly two decades. He gave it to Luke Skywalker, who lost it when Darth Vader struck off his son's hand in Cloud City.
Arriving on the planet Christophsis, he encountered a woman named Gretta, who took him to Dr. Cuata. While Cuata worked on Skywalker's lightsaber, he gave Luke a blank crystal, which after receiving a vision of Yoda, turned green.
During their final conflict with Palpatine, Rey managed to use The Force to teleport Luke Skywalker's lightsaber into the hands of Ben, as she wielded Leia's.
Ben Solo's Blue-Bladed Lightsaber
Ben Solo used a lightsaber with a typical hilt that released a blue plasma blade. Ben Solo, while training as a Jedi Padawan under his maternal uncle Luke Skywalker, made and used a blue single bladed lightsaber.
In The Last Jedi, during Rey and Kylo Ren's confrontation in Snoke's throne room, Luke's original lightsaber was split in half, and as shown later on in the movie, the crystal had been divided too, but in The Rise of Skywalker, which takes place one year after the previous movie, Rey is shown to have rebuilt it.
The lightsaber's redesign was a byproduct of the bleeding process that damaged its kyber crystal, rendering it dangerously flawed and unstable, and necessitating the lateral vents were meant to prevent the cracked kyber crystal from overloading.
Gathering his strength, Kylo hurled his Sith lightsaber into the sea. Ben Solo had returned. Ben returned to Exegol, where Rey had confronted Palpatine. She gave him the Skywalker lightsaber, which he used to strike down the Knights of Ren.
Even though Kylo Ren uses a red lightsaber, harnesses the dark side of the Force, and wears a cape, he is not a Sith. Because of that, he can never hold the title of Darth. Instead, he was just a chaotic mess of the dark side (until he eventually found his way back to the light).
He poured his malice and darkness into his Kyber crystal to bleed it. But it turned out that he could lie to his feelings, and this caused the bleeding process to mess up. As such, the Kyber crystal became an unstable cracked object reflecting Kylo Ren's unstable personality.
As for why Luke uses his blue lightsaber instead of green in this projection, he knows it will impact Kylo Ren, who believes the Anakin Skywalker lightsaber should belong to him.
Why Did Rey Bury the Lightsabers? Since Luke and Leia, her masters, have become one with the Force, this is her way of honoring them by putting their weapons to rest. It also shows that Rey is burying the past while carrying it with her — both in her spirit and in the lightsaber she now wields.
There, Rey unveiled her finished, single-bladed weapon after burying the two lightsabers of her mentors, Luke Skywalker and Leia Organa, at the ruins of the Lars homestead—the former place of residence of the Skywalker family.
After defeating her grandfather, Emperor Palpatine, and ending the Sith threat (at least for now), Rey journeys to Tatooine. There, outside Luke's childhood home, she buries his and Leia's lightsabers, before igniting her own, crafted from the staff we first saw her wield on Jakku.
This can be seen in the novel starwars.wikia.com/wiki/Rogue_Planet. It's because of his mastery of sorsue (sorry for my bad spelling.) Well if you want the ACTUAL reason it because in the original 3 films the Green Light Sabre didn't exist until after Obi Wans death.
Leia's lightsaber was a blue-bladed lightsaber used by Princess Leia Organa during her time as a Jedi Padawan training under her brother Jedi Knight Luke Skywalker.
Any kyber crystal could be bled by a Force user, including one's own, for example, if they were a former light side practitioner and kept their lightsaber.
The crossguard blades allow Ren's saber to operate safely – his weapon is constructed around a dangerously flawed kyber crystal, which would be overloaded if not for the lateral plasma vents that create the quillons.
Given that she studied Luke's ancient Jedi texts and was trained by Leia, Rey most likely used a variation of Form VI, Niman. Form VI, Niman, takes elements from the previous five forms and combines them into a pastiche that's proficient in all situations, but lacks the specialization of other forms.
1 Darth Sidious
As well as being a gifted bladesman Sidious' connection to the Dark Side is extremely powerful, granting Sidious the ability to conduct force lightning.
Rey didn't become a Sith Lord imbued with the soul of Palpatine because she didn't kill him, he ultimately killed himself. His greed, recklessness, and thirst for power were his undoing.
Lightsaber Colors Used to Matter
A brief who's who of users with blue lightsabers includes Obi-Wan Kenobi, Luke Skywalker, Anakin Skywalker (Hayden Christensen, pre-youngling slayer), Shaak Ti, and Count Dooku (Christopher Lee, pre-dark side/ass handed to him by Yoda).
He gave it to Luke Skywalker, who lost it when Darth Vader struck off his son's hand in Cloud City. The lightsaber then became part of Maz Kanata's collection of Jedi curios, where it called to the scavenger Rey. She wielded it in defeating Kylo Ren, then brought it to Ahch-To and offered it back to Luke.
It appears rarely in the Star Wars universe—so rarely, in fact, that the current canon recognizes only one carrier of a white lightsaber. Ahsoka Tano, the former Jedi Padawan who aided in the rebellion against the Galactic Empire, is acknowledged as the sole possessor of the white lightsaber.