Anakin Skywalker's lightsaber has been a central fixture of the Star Wars galaxy ever since Obi-Wan first presented it to his son, Luke, in A New Hope. It always held the weight of legacy in its hilt due to the legendary status of the former Jedi, only for it to be revealed that it was also the same weapon used to hunt down and destroy many Jedi Knights, including the younglings at the Jedi Temple, after Anakin turned to the dark side and became Darth Vader.
That same lightsaber was eventually lost when Vader himself severed it from Luke's arm, along with his hand, with the saber falling into the depths of Cloud City, only to resurface decades later when it calls to Rey from the basement of Maz Kanata's palace. Now the saber isn't even considered Anakin's or Luke's, with Lucasfilm marketing, explicitly referring to it as "Rey's" saber. But it's not the only weapon to be wielded by the fallen Jedi, as Vader is probably most well known for the crimson blade he wielded in each movie from the original trilogy.
Now, thanks to Marvel Comics' Darth Vader #1, from writer Charles Soule and artist Giuseppe Camuncoli, the story behind the more sinister of Anakin's weapons is finally being told.
"Where is Your Lightsaber, Lord Vader?"
Picking up during the ending of Revenge of the Sith, right after Anakin gets his fancy new black armor, the comic reveals that the infamous "NO!" yelled by the new Sith not only damaged the droids and medical equipment, but also knocked back Sidious himself. The Dark Lord of the Sith attacks Vader, taunting his new apprentice, saying "where is your lightsaber, Lord Vader? Use its power! Defend Yourself!" When Vader tells him it had been lost during the duel with Obi-Wan on Mustafar, Palpatine corrects him: "That blade belonged to another. A Jedi. You are a Sith."
It was already revealed in the Ahsoka novel that Sith lightsabers are red due to a the kyber crystal inside being made to "bleed" when a Sith exerts his control over it. The comic goes into more detail, with Palpatine saying that Sith lightsaber blades are indeed colored by their crystals, just as Jedi blades are. But since the Sith don't manufacture these kyber crystals, nor do they excavate them from natural sources. Sith steal their kyber crystals from the lightsabers of Jedi. After a crystal is extracted, the Sith who stole it pours all of his or her pain and rage into the crystal, effectively torturing the living force within the kyber crystal, causing it to "bleed," turning it red. A process that is actually reversed b Anakin's former Padawan, Ahsoka Tano, when she steals her kyber crystals from an Inquisitor, turning the blades white.
This continues a trend in modern Star Wars canon's depiction of the Force that shows the Sith as usurpers, not simply tapping into a "dark side" of the mystical energy field, but actually corrupting its natural flow, perverting its original intent to serve their will, as opposed to surrendering to its will as some of the more wise Jedi, like Qui-Gon Jinn, Yoda, and Obi-Wan Kenobi urge in their teaching.
"The saber of a Sith is not given. It is taken."
With Order 66, and contributions from Vader himself, having just killed thousands of Jedi, Grand Vizier Mas Amedda is hosting a public destruction of the Jedi weapons, declaring the Empire safe from their "Separatist plots" after their "attempt to assassinate" Emperor Sheev Palpatine. Vader notes that Palpatine is not giving him one of these lightsabers, deducing that it must be because "the saber of a Sith is not given. It is taken."
In what appears to serve as a sort of right of passage for the new Sith apprentice, Darth Sidious takes him to an unnamed planet on the Mid-Rim, where he leaves him unarmed to track down his Jedi victim, claim his weapon, and bend its kyber crystal to his will in the black hilt of his new lightsaber. The obvious question is who will Vader's victim be? Jedi bear a much more intimate connection with their Kyber crystal, and Ahsoka even recognized the presence in the crystals she claimed from the Inquisitor for her own. Will the Jedi that supplies Vader's new kyber be one familiar to fans, and will this in any way reflect on his continued legacy?
Regardless, the lightsaber inherited by Luke - and later by Rey - was only the property of Anakin for a few years during the Clone Wars, whereas this new blade, presuming he doesn't need to regularly replace it as well, has several decades of legacy behind it, so its only fitting for the very first story in Vader's post-Mustafar career to revolve around its theft and construction, including a depiction of the former Jedi bleeding one of the crystals with which he used to share a much more intimate bond.
Whatever happens, with hundreds - if not thousands - of Jedi possibly still on the loose, the new Sith Apprentice has his work cut out for him once he claims his new crimson blade and continues to finish what Palpatine started with Order 66.