One thing the Star Wars movies never addressed is what happens to the lightsabers of dead Jedi, but a new canon novel explains the Jedi Order preserved the kyber crystals inside the Jedi Temple. Ever since George Lucas' first Star Wars movie released, lightsabers have been a cornerstone of the franchise and a significant part of its allure. The fact these weapons are wielded by warriors with remarkable powers, and can not only cut down anything in their path but also deflect blaster shots, is why they've become so iconic.
To top off their intrigue, lightsabers come in various shapes, sizes, designs, and colors, and they're used in different ways, considering there are several lightsaber combat forms that Jedi and Sith both master throughout their lives. Constructing a lightsaber itself is a process unique to Force users, and one thing they must acquire to complete the assembly is obtaining a kyber crystal, which is what powers the lightsaber and gives it its color. And finding the right kyber crystal to use is a journey all Padawans have to complete alone.
When a Padawan searches for their kyber crystal, they have to find the one that suits them, essentially building a bond with it through the Force. Although anyone can use the lightsaber, the crystal itself is unique to the person who found it. So to maintain the religious aspect of the Jedi Order as well as their viewpoint on death, the Jedi would take the kyber crystals from the lightsabers of fallen Jedi and use them to construct an archway inside one of the meditation chambers in the Jedi Temple on Coruscant. It became known as the Kyber Arch, and on occasion, Jedi would try to scale it as a challenge from the Force.
The Kyber Arch is first revealed in the Star Wars novel Into the Dark by Claudia Gray; it's one of the early installments in Lucasfilm's The High Republic initiative, which takes place hundreds of years before the events of the Star Wars prequel trilogy and depicts a very different Jedi Order than the one viewers are used to seeing in the movies and TV shows. At that point in the timeline, the Jedi numbered in the thousands and acted more as peacekeepers than they did politicians. Furthermore, they had an alternate outlook on the Force than the Jedi Knights and Jedi Masters did during the events of the Skywalker saga.
With Wayseekers, multiple Jedi Grand Masters, and an acceptance of affection among members, the Jedi Order of the High Republic era was a far cry from the one shown in Lucas' films. Part of that is why the Kyber Arch may not have been in use during the prequel era - of course, there's also the production reason; it simply didn't exist yet - but that doesn't mean the Jedi didn't continue to keep the lightsabers of fallen Jedi. In canon, it's been noted Tarre Vizsla's Darksaber was kept in the Jedi Temple, as was Qui-Gon Jinn's lightsaber when he died. Anakin Skywalker's lightsaber wasn't, however, because the Jedi Order had fallen when he turned to the dark side - and so, Obi-Wan Kenobi kept it for Luke Skywalker.
