Covenant light staff
From Halopedia, the Halo wiki
The Covenant light staff is a type of light amplifying device used by the Covenant and other related factions to increase visibility in low light environments and locations which feature dense terrain. They have been encountered by UNSC troops when assaulting Covenant encampments and sometimes ships. These devices are portable enough for Covenant troops to move them from camp to camp, or camp to ship.
They are rod shaped, with the top holding a sphere, which is essentially the bulb. It has a handle and can be activated by a switch near the top on the side of the handle opposite the bulb. It can be found on the first Halo game dotted all around the level Assault on the Control Room. They have been in use since Halo: Combat Evolved, but have had slight differences in appearance. They operate by emitting a blue plasma glow whenever they detect motion nearby, conserving energy by automatically shutting off once the motion leaves the immediate area.
There are minor differences between the versions; in Halo: Combat Evolved, they emitted an actual plasma flame, while in Halo 3 they extend slightly and then emit a soft blue light.
List of appearances