Master of Iron: Book 2 of the Bladesmith Duology - Tricia Levenseller

Eighteen-year-old Ziva may have defeated a deadly warlord, but the price was almost too much. Ziva is forced into a breakneck race to a nearby city with the handsome mercenary, Kellyn, and the young scholar, Petrik, to find a magical healer who can save her sister's life. But the plan goes awry and Ziva and Kellyn are captured by an ambitious prince. Once again, Ziva is forced to use her powers for sinister purposes, magicking dangerous weapons meant for world domination. The forge, once her safe space from anxiety, is now Ziva's prison - and she's not sure how much she'll need to sacrifice to keep herself and Kellyn alive.