'arbalestrier' originates from Old French, specifically the word 'arbalestier', where 'arbaleste' meant 'crossbow' and the suffix '-ier' formed an agent noun.

'arbalestrier' traces back through Old French 'arbaleste' / 'arbalest' (meaning 'crossbow'), which itself derives from Late Latin 'arcuballista' (from Latin 'arcus' meaning 'bow' + Greek/Latin 'ballista' meaning 'missile-thrower'); the agent-form '-ier' produced the term for a person who used the weapon and this entered Middle English as variant agent nouns such as 'arbalestier' and later 'arbalestrier'.

Initially it referred to the crossbow or the weapon ('crossbow'); over time the sense shifted (or extended) to denote the person who operated the weapon, i.e., a crossbowman.