'equal-powered' originates from Modern English, combining the adjective 'equal' (ultimately from Latin 'aequalis') and the past participle 'powered' (from 'power', ultimately from Latin roots such as 'potentia'/'posse'), where 'aequalis' meant 'level, even' and the root of 'power' meant 'ability or strength'.

'equal' changed from Latin 'aequalis' to Old French 'egal' and then to Middle English 'equal'; 'power' changed from Latin 'potentia'/'potere' through Old French (e.g. 'pouvoir') into Middle English 'power' and, in Modern English, the compounds combining these elements produced forms like 'equal-powered'.

Initially, 'equal' meant 'level, even' and 'power' meant 'ability or strength'; over time the compound 'equal-powered' came to mean 'having the same level of power' as its current usage.