noun
light weapon; light firearm
Military and technical term for portable weapons such as rifles, submachine guns, and light machine guns, as opposed to heavy weapons like artillery.
歩兵部隊は軽火器で武装していた。
The infantry unit was armed with light weapons.
この条約は軽火器の取引を規制している。
This treaty regulates the trade of light firearms.
小火器 specifically means small arms (handguns, rifles), a subset of 軽火器; 軽火器 can include slightly heavier crew-served weapons like light machine guns.
Compound of 軽 (light) and 火器 (firearm). The term is a modern technical coinage, likely influenced by English 'light weapon' or similar military terminology.