which Faith?
That little honorific is an example of "royalty means never having to give anything back." Pope Leo X created the title for Henry VIII because King Hank had written a missive against Martin Luther. After His Nibs couldn't keep control hisself around Anne Boleyn, he basically invented his own church and a subsequent Pope rescinded the title; armed with backing from its own shiny new denomination, Parliament restored the title (not being exclusively concerned about titles, King Hal also confiscated the bulk of the Roman Catholic Church's wealth and holdings). "It's good to be king," as they say.
Anyway, that little "Fidei Defensor" dealio can apparently mean whatever faith they want it to mean at the moment.
MarQ