'armamentary' originates from Late Latin, specifically the word 'armamentarium', where 'armamentum' meant 'equipment or implements (of war)'.

'armamentary' derived via Medieval/ Late Latin 'armamentarium' and appeared in English usage influenced by the noun 'armament' and the adjectival suffix '-ary'.

Initially it referred chiefly to the place or collection of arms ('a repository of equipment'), but over time it has also been used adjectivally to mean 'relating to weapons or armaments'.