Humbler stun device
From Halopedia, the Halo wiki
The Electric Baton is a nonlethal weapon used by the UNSC Marines mostly for "motivating" others in a painful but relatively harmless way.
When the Spartan children first arrived at Reach in 2517, Electric Batons were used by Chief Petty Officer Mendez to "motivate" them at first, though they soon grew to cooperate with him, and the devices were not needed.
It is possible that these devices could have other uses particularly with police, but none are mentioned.
