Flashstick
From Wookieepedia, the Star Wars wiki.
A flashstick was a device similar to a stun baton that was developed and used by law enforcement on Drall. When the flashstick made contact with a target, the weapon emitted a powerful and blinding flash, helping to subdue the target and reduce its ability to flee or otherwise resist. Because Drall were extraordinarily sensitive to bright light, it rendered them effectively stunned. It was less effective on other species of humanoids that did not possess a sensitivity to light: the subject was blinded, but not incapacitated. The device weighed one kilogram and was widely available.
