Luke’s Green Lightsaber
Luke’s original blue lightsaber, owned by his father Anakin Skywalker before him, is a hugely significant item in these movies, and its destruction at the end of The Last Jedi comes as a big blow to Rey. You might have missed it, though, but Luke’s second lightsaber also makes a brief appearance in the film.
First of all, you’ll remember how Luke lost his original saber when Vader chopped off his hand in The Empire Strikes Back. By Return of the Jedi, he had replaced it with a green model. In The Last Jedi, this lightsaber appears in the flashback sequence to the night Ben Solo burned down Luke’s Jedi school. In a memorable moment, Luke almost uses it to murder his nephew in his bed when he senses the evil within him.
As for why the green lightsaber is nowhere to be seen in the present day scenes, no explanation is given. Though seeing how Luke throws his blue lightsaber away when Rey first gives it to him, it’s not too much of a stretch to assume he flung it into Ahch-To’s sea.