Star Wars: The Last Jedi - 10 Ways It Sets Up Episode IX
4. Rey Building A Lightsaber (Or Finding Luke's Green One)
Midway through The Last Jedi, Rey and Kylo get into a mental tug-of-war over Luke's blue lightsaber, which was previously owned by his father, Anakin.
This stress causes the lightsaber to snap clean in half, leaving Rey weaponless for the rest of the movie.
But surely, she won't be weaponless for long. Lightsabers are associated with the Jedi as much as the Force is, and since Rey is now the last Jedi, she'll need a signature weapon of her own to wield in Episode IX.
There are a lot of possibilities here: she could rebuild the broken blue one, passing it down to the next generation of Jedi when the time comes, as a memento of the Skywalker legend; she could construct her own unique saber, as Luke, Kylo Ren, and others have done before her; or, she could hunt down Luke's green blade, which was presumably lost in the rubble of his destroyed Jedi Academy.
It would be very strange to have a Star Wars movie where the Jedi hero doesn't carry a lightsaber, so one of these options is an absolute certainty, and given Rey's skill with melee weapons, it makes sense for her to have a lightsaber of her own.