those ages at Marriage were low even by Manx standards - probably a sign that they were not well off (or a child on way or both).
There was a John Ward boot and shoe maker in Duke St in 1837 - what did daniel do and why was he in Douglas aged 18 ? Irish records thanks to fire in Irish rec office in 1921 should give you an interesting problem - especially as Ward is I think is relatively common !
Taggart is a common Manx name so best of luck - Douglas at that time was attracting many from the countryside