Thief's magic / Trudi Canavan.

In a world where an industrial revolution is powered by magic, Tyen, a student of archaeology, unearths a sentient book called Vella. Once a young sorcerer-bookbinder, Vella was transformed into a useful tool by one of the greatest sorcerers of history. Since then she has been collecting information, including a vital clue to the disaster Tyen's world faces. Elsewhere, in a land ruled by the priests, Rielle the dyer's daughter has been taught that to use magic is to steal from the Angels. Yet she knows she has a talent for it, and that there is a corrupter in the city willing to teach her how to use it, should she dare to risk the Angels' wrath. But not everything is as Tyen and Rielle have been raised to believe. Not the nature of magic, nor the laws of their lands. Not even the people they trust.