Disciple of Sin (The Last Sin Book 1) by J. W. Weld

Forged by Lady Sin to be her ultimate weapon, Jacob uncovers the truth about the woman who made him. Cast out but determined to prove himself her equal, he joins sellswords infiltrating a town ruled by crime lords. Their mission: stop a curse that wakes the dead. Sin taught him that trust is a weakness. To survive, he’ll have to prove her wrong.