The following contains spoilers for The Mandalorian Season 3, Episode 2, "Chapter 18: The Mines of Mandalore," streaming now on Disney+.
Mandalorians have always been known for their impressive weapons caches, and Din Djarin is no exception. He started The Mandalorian sporting an IB-94 blaster pistol and an Amban phase-pulse blaster. As the series continued, Mando improved his arsenal a few times. The Armor made him a whistling bird, and he acquired a spear made of pure beskar. However, Mando's greatest weapon was the Darksaber, which he earned by defeating Moff Gideon.
Mando got the Darksaber in The Mandalorian's Season 2 finale, and fans got to see it in action during The Book of Boba Fett. Unfortunately, there was a problem. It was too heavy for Mando to effectively use. There were a few theories why a supposedly weightless blade was so heavy. Yet there was no definitive explanation. Now, "The Mines of Mandalore" has further complicated the issue.
Why the Darksaber Fought Against Mando
Lightsaber blades are weightless, but that doesn't mean that they always feel that way. They have a gyroscopic effect that makes them feel heavy to an untrained wielder, but Star Wars Rebels gave more of an explanation. In "Trials of the Darksaber," Kanan told Sabine Wren that when someone wields a lightsaber, his or her thoughts fuel the blade's energy. So, if they were off-balance or conflicted, then the blade would feel heavy. The Armorer said as much when she told Din that he was fighting against the blade.
While that makes sense, there appeared to be something more at work. Star Wars fans know that Kyber crystals are essentially sentient in the Force. So -- just like The Armorer indicated -- Mando's will was opposed to the Darksaber's will, but why? That might go back to Mandalorian history. The Darksaber indicated the right to unite and rule all of Mandalore, but Din Djarin immediately shirked that responsibility. As soon as he won the weapon from Moff Gideon, he tried to give it to Bo-Katan. Thus, it wasn't just Mando fighting the blade. The Darksaber was fighting against Mando -- because he wasn't worthy to rule.
Why Bo-Katan Could Lift the Darksaber When Mando Couldn't
All of that could still be true, but "The Mines of Mandalore" made things more complicated. The episode showed Mando getting captured by a cyborg spider creature, so Grogu high-tailed it back to Bo-Katan for help. She didn't want to, but she couldn't refuse Grogu. So, Bo-Katan went to save Mando, and while she was fighting the cyborg spider, she found the Darksaber lying on the ground. Having used it before, she picked it up and used it to defeat the creature. The odd thing was, she didn't have any problems lifting the blade.
Supposedly, the Darksaber curses the efforts of anyone who doesn't win it in combat. That's what happened to Bo-Katan with the Great Purge, but that didn't prevent her from actually wielding the blade. If anything, Bo-Katan should have been less "worthy" to wield the Darksaber because she had abandoned the Creed long ago. All of that goes to show that Mando not being able to lift the Darksaber has nothing to do with how he acquired the blade or his failing the Creed.
Accordingly, the best explanation is still that the Darksaber doesn't personally approve of Mando. Bo-Katan wanted to unite and rule Mandalore (even if she'd temporarily given up), so she could lift the blade. The same went for Moff Gideon. Even if he had the wrong idea, he did want to rule Mandalore with the Darksaber. Meanwhile, Mando had given up that right, so the Darksaber was doing its best to find a new wielder. Thus, it looks like Mando won't be able to use the Darksaber until he takes responsibility as a Mandalorian leader.
New episodes of The Mandalorian Season 3 air Wednesdays on Disney+.