from what i know, and i could be wrong, sire was only used as a term of respect to lords and males of some standing, not just anyone that had a dick. that or to claim patriarchal parentage, even going back a few generations. it's sort of strictly for a lord or the monarchy now, but pretty sure it was used the same as 'lord' was; to people of station. i can't say i've ever heard of a priest being called sire, but like i said, i could be wrong.