The Reader by Hope E. Davis

Ralheim is at war. When Runa’s twin brother skips his call to service, the Viscount comes to their home to collect him. Never one to back down from a challenge, Runa disguises herself and enlists in his place.
Before she can reach the front lines, however, she is deemed too thin and conscripted into service at the Viscount’s ostentatious palace instead.
As one of the Seid, Runa learned the language of magic as a child. Unfortunately, Viscount Adis is aware and ready to exploit any edge he can to win his petty war, but he isn’t the only one who is willing to go through great lengths to attain magic…

Perfect for fans of the plot of Quicksilver and the unique magic system of One Dark Window, The Reader is an adult romantasy with dystopian themes written for those who recognize true power is not associated with stature, position, or gender.