Complex sentence: Justinian next appointed Pope Pelagius I, holding only a "sham election" to replace Vigilius; afterwards, Justinian was content to be limited to the approval of the pope, as with Pope John III after his election.
Split into simpler sentences: Justinian next appointed Pope Pelagius I, holding only a "sham election" to replace Vigilius. Afterwards, Justinian was content with power of approval of the Pope, as with Pope John III after his election.