Complex sentence: Otto I believed that the power Louis IV was sufficiently diminished and proposed a reconciliation with the Duke of the Franks and the Count of Vermandois: from that point on, Otto I was the new arbitrator in the West Francia.
Split into simpler sentences: Otto I believed that the power Louis IV was sufficiently diminished and proposed a reconciliation with the Duke of the Franks and the Count of Vermandois. From that point on, Otto I was the new arbitrator in the West Francia.