Other than the Dark Era books, is there a source book for Chronicles of Darkness for running games set in the Dark Ages? The Dark Era books have good thematic information but are a bit light on mechanical aspects like equipment, skills, merits, and that kind of thing.
No, there are no specific supplements for Chronicle of Darkness that deal with the mechanical minutiae of each Dark Eras setting. A list of books in the COFD and NWOD series can be found here: http://www.wodcodex.com/wiki/Books . Happy hunting!