An Etymological Dictionary of the German Language/Annotated/Mesner
Mesner, masculine, from the equivalent Middle High German męsnœre, męssenœre, masculine, ‘sexton, sacristan’ (the latter connected with Messe), from late Old High German męsinâri (not messinâri), masculine, based on Middle Latin *masinarius for mansionarius, ‘custos et conservatoraedis sacrae, aedituus, ostarius’; Middle Latin mansionarius was also an official in the court of the Frankish kings (Middle Latin mansio, ‘house,’ equivalent to French maison). Compare Küster and Sigrist.