Complex sentence: The King of Spain also bears the nominal title of Archduke of Austria as part of his full list of titles, as the Bourbon dynasty adopted all the titles previously held by the Spanish Habsburgs when they took over the Spanish throne.
Split into simpler sentences: The King of Spain also bears the nominal title of Archduke of Austria as part of his full list of titles. This is because the Bourbon dynasty adopted all the titles previously held by the Spanish Habsburgs, when they took over the Spanish throne.