Obi-Wan Kenobi Uses a Red Lightsaber for the First Time (And Why)
In an episode of The Clone Wars, Obi-Wan Kenobi teamed up with Ventress to escape Maul and Savage, but to do so he needed to use a red lightsaber.

Obi-Wan Kenobi is one of the few major Star Wars characters not seduced by the dark side, but in an episode of Star Wars: The Clone Wars, the Jedi Master wields a Take the red lightsaber traditionally synonymous with Sith. In The Clone Wars season 4, episode 22, "Revenge", Kenobi is kidnapped by Darth Maul and the Savage Queen. He forms an unlikely ally with former Sith apprentice Asajj Ventress. Ventress is looking for revenge on Savage who betrayed her earlier. Moore also wanted revenge on Kenobi, who chopped him in half in Episode I: The Phantom Menace.
During this battle, Ventress gave Obi-Wan one of her two red lightsabers so he could defend himself. This is one of the few times audiences see Obi-Wan Kenobi wield a lightsaber that isn't his own, and it's the only time he wields a red lightsaber in canon. While other Star Wars characters (such as Ahsoka Tano) wield multiple different lightsabers, Obi-Wan is one of the few characters who doesn't build a new lightsaber for himself at any stage. Even Luke Skywalker had to rebuild his lightsaber after losing it at the end of Empire fight back. Even though Obi-Wan stole his blue lightsaber back from Maul rather quickly during their fight, it was cool to see the Jedi Master wielding a different colored lightsaber.
How Maul Brought Out The Dark Side in Obi-Wan

Although Obi-Wan was seen as a wise Jedi Master in Star Wars, Maul was able to bring him closer to the dark side, especially after killing Obi-Wan's master, Qui-Gon. He's an expert at taking Obi-Wan's rage and using that rage to throw him off balance. Kenobi's duel with Maul in "Revenge" was one of the most brutal fights audiences have ever seen involving Obi-Wan, not unlike his duel with Anakin on Mustafar and their fight with Obi-Wan Kenobi. On par with the rematch in the Disney+ show. Poetically, one of Kenobi's most brutal fights comes when he's out of balance with the Force, and the only time he uses his red lightsaber.
Obi-Wan's Maul & Savage Fight Led To Maul’s Mandalorian Takeover

In The Clone Wars, when Kenobi and Ventress escape in the cockpit of Maul and Savage's ship, the brothers don't have a door to keep out the cold. Eventually, the Mandalorian Death Guard found the brothers and restored them to health. Maul and Pre Vizsla strike a deal to jointly take over Mandalore. both sides are planning However, due to mutual betrayal, Darth Maul became the leader of the Mandalorians after killing Vizsla in a duel. Maul then murdered Satine, Duchess of Mandalore, in front of Obi-Wan to emotionally hurt him. It was previously established that Obi-Wan and Satyn have feelings for each other, but due to Kenobi's dedication to the Jedi and their code, they cannot be together,
Kenobi will not fight Maul again until they are in Star Wars Rebels By. However, in The Clone Wars Season 7, Ahsoka Tano and Bo Katan Kryze lead the siege of Mandalore to capture Maul. Seeing how a duel between Obi-Wan Kenobi, Asajj Ventress, Darth Maul and Savage Opress led to such an outcome is poignantly breaking the cycle. Even if only briefly, seeing Obi-Wan Kenobi furiously wielding a red lightsaber in Star Wars: The Clone Wars was a great addition to the usual wise and balanced Jedi Master viewers have grown accustomed to in Star Wars. It is also an exciting change.