A Weapons Room was an area on a starship or within a facility where hand-held energy weapons were stored and maintained.
On a Starfleet vessel in the 2350s, hand phasers were stored and charged in a charging unit in the Weapons Room.
Circa 2359, the charging unit in the Weapons Room of the USS Starbound was sabotaged, rendering its phasers defective. (TNG novel: Survivors)