Appending a Christian dedication/invocation to a book which may be construed as pagan/heretical appears to be a standard safety practice in those times; witness Dee's "angelical" diaries. I would think that a dedication to Mary (instead of Jesus or God) would hint to a woman author. (But this is defintely not a hard rule!)
I think there is a danger of making far too much of this page. It is a very common thing to find semi-legible writing on the first and last pages of a manuscript: it marks where the scribe was trying out his pen.