The Bible of the Silver Cross is ANOTHER Lost Logia from a forgotten era, right? Kind of like the Miriage? And the Saint's Cradle?
Gee, whatever happened to that guy they could count on to dig through ancient records and ruins to discover the vital information they needed to solve incidents involving ancient doom-weapons, like Jewel Seeds and the Book of Darkness?
There's simply WAY too much ancient shit resurfacing and causing trouble for the series to throw away its ONLY archaeologist/librarian. Especially since he doubles as powerful support in a fight, even without a Device.