Truthwitch

On a continent ruled by three empires, everyone is born with a witchery, a magical skill that sets them apart from others. Now, as the Twenty Year Truce in a centuries long war is about to end, the balance of power-and the failing health of all magic-will fall on the shoulders of a mythical pair called the Cahr Awen.
The biggest thing on Safi and Iseult's minds is saving money for their planned future in the Hundred Isles. Iseult, a Threadwitch, can see the emotional Threads binding the world. Safi, on the other hand, is a Truthwitch-she always knows when a person is telling a lie. A powerful magic like that is something people would kill to have on their side-or to keep off their enemy's side-and so Safi cannot even admit what she truly is.
With the help of the cunning Prince Merik (a Windwitch and a ship's captain) and the hindrance of a Bloodwitch bent on revenge, the friends must rise above their doubts and fight to learn who they are and what they are made of, if they are going to stay alive and preserve the balance of their world.