Complex sentence: Lady Margrethe was the widow of a local nobleman who had asked Bishop Svend to convert Veng Abbey into a convent for nuns with herself as the abbess which position brought with it a guaranteed annual income.
Split into simpler sentences: Lady Margrethe was the widow of a local nobleman. She had petitioned Bishop Svend to convert Veng Abbey into a convent for nuns with herself as the abbess which position brought with it a guaranteed annual income.