While a specific reason isn't given, fans have some convincing theories as to why he chose this lightsaber over his green. Looking at it from a filmmaking point of view, some believe it's meant as a hint to Luke's Force projection.
Luke's use of the blue lightsaber – his father Anakin's blue lightsaber – is purely to taunt Kylo Ren (Ben Solo). In retrospect, Kylo Ren should have noticed it, but he was too blinded by rage to.
Why does Luke's lightsaber change from blue to green?
The main reason for the change was that during the filming of Return of the Jedi, the crew realized that the blue saber did not look right during the battle with Jabba the Hutt. When shot in daylight, the blue would blend with the color of the sky, so George Lucas and his crew decided to make the change.
How does Luke get Anakin's lightsaber in The Last Jedi?
After defeating Vader in a duel on Mustafar, Obi-Wan Kenobi took Anakin's lightsaber with him into exile on Tatooine. Obi-Wan gave the lightsaber to Anakin's son Luke, who used it in taking his first steps along the Jedi path.
What happened to Luke's green lightsaber in The Last Jedi?
Having lost his nephew to the dark side, along with his remaining students, who were killed in the destruction of his Jedi temple, Skywalker brought his lightsaber to the planet Ahch-To where he lived in self-imposed exile and isolation. After his death, the native Caretakers took possession of Skywalker's lightsaber.
Why Luke Uses the Blue Lightsaber in The Last Jedi
What is the rarest lightsaber color?
The black lightsaber, or Darksaber to give it its proper name, is one of the rarest lightsabers in Star Wars canon. Despite its rarity in canon, anyone who has seen the second season of The Mandalorian is likely to be familiar with the Darksaber.
Why did Luke have a perfectly replicated hand in Return of the Jedi, and an obviously mechanical hand by the time of The Force Awakens/The Last Jedi? It's likely the same mechanical hand. It was tested at the end of ESB, and got shot during ROTJ, if you recall. Then he wore a glove over it for the rest of the film.
The fate of Luke Skywalker's old lightsaber appeared to be symbolic of his philosophy; it was shattered in a Force tug-of-war between Rey and Kylo Ren. Even its Kyber Crystal was broken. And yet, in spite of that, Rey succeeded in repairing the lightsaber in Star Wars: The Rise of Skywalker.
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.
Fans know about the materials she used to build the hilt itself, but lightsabers can't work without a kyber crystal to power them. So, where did Rey get hers? The most popular theory is that this kyber crystal once belonged to Luke Skywalker and the 'saber he used between Empire Strikes Back and Return of the Jedi.
Qui-Gon's apprentice, Obi-Wan Kenobi, then used the same lightsaber to defeat Maul after losing his own. After the battle, the weapon was later returned to the Jedi Temple. With the advent of the Great Jedi Purge, the blade again fell into the possession of Kenobi, who went into hiding on the planet Tatooine.
Leia Organa's lightsaber was a blue-bladed lightsaber powered by a kyber crystal in the core of the hilt. It was silver and copper in color and featured mother-of-pearl inlays. Organa's weapon was considered a work of art, having an elegant symmetry with silver and gold hues that evoke to her upbringing on Alderaan.
What did Darth Vader adjust on Luke's lightsaber in Return of the Jedi?
Luke Skywalker's green lightsaber in Return of the Jedi represented his status as a Jedi Knight and his ability to successfully construct his own weapon. Vader did not adjust Luke's lightsaber during their confrontation. He acknowledged Luke's accomplishment.
He knew he had to stop Kylo but didn't want to kill him, so appearing as a projection was the sure way of keeping him alive. Not only would a physical attack against Kylo result in his likely death, but it also would have pushed him even further to the dark side if it failed.
The lightsaber Kylo Ren longed for as his birthright was instead claimed by Rey on Starkiller Base. You need a teacher! I can show you the ways of the Force!" After incapacitating Finn, Ren attempted to summon the lightsaber to him, regarding it as his own property due to its history.
Thanks to healing techniques she learned from ancient Jedi texts, Rey mended Anakin's Kyber crystal and repaired the hilt, restoring it to working condition. The Kyber crystal and (and subsequently, the blade) remained blue, however. Rey would later construct yellow-bladed lightsaber.
Despite being enemies, Rey and Kylo Ren share a connection called a 'Force dyad' and eventually become romantically involved with one another. Following Palpatine's final defeat and her own resurrection, Rey adopts the name Rey Skywalker to honor her mentors and their family legacy and renounce her lineage.
By the time Rey touches the weapon, Anakin has long been redeemed, and the essence inside the Skywalker lightsaber is constantly calling her to learn the ways of the Jedi and fight against the dark side in his place.
Kylo develops a close relationship with Rey and starts feeling genuine affection towards her, so when Snoke reveals that he had manipulated their bond and tortures her in front of Ren, he looks furious at his master. Thus, when Snoke orders Ren to kill Rey, he chooses to save her and kill his master instead.
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.
Kylo Ren's "unstable" lightsaber was designed to kill. Knowing Makashi, he would become a much more dangerous foe as he could disarm and eliminate his opponents far quicker without the need to endure a long, intense fight. Sadly, he didn't learn Form II as there was no one around to teach him during his younger days.
Luke also noted that the weapon possessed superior balance to Anakin Skywalker's second lightsaber. Possibly as a result of utilizing a synthetic crystal, the lightsaber made a distinctive snap-hiss sound when activated, which was a different sound to that emitted by his father's weapon.
As a Dark Lord of the Sith, Vader oversaw the training of the Inquisitorius—a group of fallen Jedi who turned against the Jedi Order in the aftermath of Order 66. To teach his Jedi hunters a lesson in the pain of loss, Vader dismembered the right hand of Fifth Brother and the left forearm of Sixth Brother.
Building a lightsaber is a vital part of a Jedi's training, owing to the spiritual connection between the weapon and its wielder, so it is unlikely Luke would have simply used Qui-Gon's lightsaber rather than building his own.
