There are no Jedi in Rogue One: A Star Wars Story, but the Force is felt throughout. There are new factions, and characters that believe strongly in the Force even if they can't wield it for fantastic feats of mind and body.
One of the ways filmmakers nodded to the Force was through the use of artifacts, like Kyber crystals. Kybers were central to the storyline - they power the Death Star's massive weapon, after all. There's also the one that Jyn Erso wears around her neck, a gift from her Force-worshipping (but not wielding) mother. As it turns out, there's a Kyber crystal that we didn't see in the film, but is there, and in a weapon, just like the Jedi use a Kyber to power their lightsabers.
The Kyber is hidden within Chirrut Îmwe's staff, specifically in the metal component at the end - a component that some fans speculated would turn out to be a lightsaber component, and they weren't completely off. The "Crystal containment lamp," as it's described in the Star Wars Rogue One: The Ultimate Visual Guide by Story Group's Pablo Hidalgo, contains not a full Jedi Kyber, but "a kyber sliver."
However, this doesn't mean Chirrut was Force-sensitive, or change anything about his character. In fact, it clears up another mystery from the film. The Kyber crystals have been known to issue a harmonic sound that typically only Jedi can hear - Chirrut, likely thanks to his blindness enhancing his hearing somewhat, can hear that harmonic.
"Designed as a symbolic source of inner illumination, it also allows Chirrut to better gauge where the end of the staff is, as he can hear both the battery and crystal harmonic," it says. He listens for that during his fighting; it actually makes that already impressive fight scene even more bad ass.
It also helps explain why Chirrut was able to sense the Kyber on Jyn's necklace - it wasn't that he sensed it in the Force, necessarily, as much as he could hear the harmonic vibration of the crystal.
Star Wars Rogue One: The Ultimate Visual Guide, available now, is full of new facts about Chirrut and Baze and their weaponry, amongst other characters, weapons, artifacts, vehicles.
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