Complex sentence: The latter is likely, because the name Sigebert is unlike any in the East Anglian Wuffinga dynasty, but closely resembles the name fashions of the East Saxon royal house, suggesting that Raedwald's wife had previously been the wife of an East Saxon prince or ruler.
Split into simpler sentences: The latter is indicated because the name Sigebert is unlike any in the East Anglian Wuffinga dynasty, but closely resembles the name fashions of the East Saxon royal house. If that identification is correct, Raedwald's wife had previously been the wife of an East Saxon prince or ruler.