Graceling by Kristin Cashore
Katsa has been blessed with a gift for killing, "a grace." She is forced to play the role of thug enforcer for the king. She ends up fighting a different battle.
I think I would have liked Graceling more a few years ago in my teen/pre-teen era. It was somewhat sanitized since its target audience is younger than me. It's a great start for a series and I felt that perhaps the story itself could have been longer, but again it's for a younger audience so I understand. Unfortunately, it lacks a certain amount of intensity and depth, which make some other YA books much better.
The magic system in this book isn't so much magic as it is simply those who have special abilities so perhaps more akin to super heroes rather than a magic system. It's certainly an interesting take on how something like this would impact a world.