The Lady of the Mark - The Men of the Mark, #1

Shaila will soon become the first woman to join a deeply guarded guild of warriors, The Men of the Mark. Together, they fight to end the civil war that's left half their country to die of starvation and disease. But Shaila's presence in the guild stirs a long-hidden corruption within their ranks, and she soon finds herself fighting for her life on two fronts. She's determined to smite both evils but must do so while guarding a deep and dangerous secret: her love for her Master and mentor, Drauses. Master Drauses is one of the most notorious Men of the Mark in history.
His comrades wish him to lead someday, but he doubts himself, especially after he violates the guild's strict moral codes by falling in love with his new ward. When their enemies move to strike them down at their weakest moment, Drauses must choose to step up or step aside as he struggles to balance honor and heart in a world that lacks both.