In his lab on the Imperial throne-world, Darth Sidious kept a number of stolen Jedi lightsabers in case he needed them, one of which was blue-bladed
In 10 ABY, Luke Skywalker destroyed a bunch of Sidious's clones, but Sidious's essence moved into one of the clones that Luke hadn't destroyed yet and the newly-possessed clone grabbed his blue-bladed lightsaber from the wall of the lab and used it to duel Luke. He won the duel and got Luke to turn to the dark side and become his apprentice.
Later in 10 ABY, he discovered onboard his Super Star Destroyer Eclipse that Luke renounced the dark side thanks to the efforts of his twin sister, Leia Organa Solo. Enraged, Sidious used his blue-bladed lightsaber to attack Luke. Despite the Sith Lord's ferocious power, he was caught off guard by Skywalker. Mere minutes later, the Eclipse was destroyed along with Sidious's clone and his stolen lightsabers.
Darth Sidious using the lightsaber to battle Luke Skywalker.
In his lab on the Imperial throne-world, Darth Sidious kept a number of stolen Jedi lightsabers in case he needed them, one of which was blue-bladed
In 10 ABY, Luke Skywalker destroyed a bunch of Sidious's clones, but Sidious's essence moved into one of the clones that Luke hadn't destroyed yet and the newly-possessed clone grabbed his blue-bladed lightsaber from the wall of the lab and used it to duel Luke. He won the duel and got Luke to turn to the dark side and become his apprentice.
Later in 10 ABY, he discovered onboard his Super Star Destroyer Eclipse that Luke renounced the dark side thanks to the efforts of his twin sister, Leia Organa Solo. Enraged, Sidious used his blue-bladed lightsaber to attack Luke. Despite the Sith Lord's ferocious power, he was caught off guard by Skywalker. Mere minutes later, the Eclipse was destroyed along with Sidious's clone and his stolen lightsabers.