'ensaddle' originates from the prefix 'en-' (from Old French/Latin influence) combined with the noun 'saddle' (Old English 'sadol').

'saddle' comes from Old English 'sadol' and through regular phonological development became modern English 'saddle'; the verb-forming prefix 'en-' (from Old French/Latin) was attached to form 'ensaddle' meaning 'to put a saddle on'.

Initially it literally meant 'to place a saddle on (an animal)'; over time it retained that literal meaning and also developed a figurative sense of 'to burden or to load (someone) with responsibility'.