Complex sentence: St Colman was the son of Queen Rhinagh and her husband the chieftain Duac; and while still in the womb had a prophecy that he would surpass all others of his lineage.
Split into simpler sentences: St Colman was the son of Queen Rhinagh and her husband the chieftain Duac. While she carried the child in her womb she heard a prophecy that her son would be great man and surpass all others of his lineage.