The story follows a man who is described as a physically large and strong warrior. I believe he fights primarily with a sword. He is described as somewhat of a wanderer, going wherever there is action. The setting is a magical world where there are magicians and they derive their power from a flow of energy, described as colorful balls that flow along the ground in sort of currents or streams (this energy was only visible by magicians I believe, though you could learn the skill with practice). In this world, girls would avoid being out at night because that's when evil creatures would come out, and there was one entity that was especially feared.
The warrior comes to meet a magician in a town. It is a woman who makes a living creating wards for people and their homes. I believe there is then some sort of incident in the town and thus begins their journey to ultimately confront an evil king like person who lives in the center of a dark and evil forest (this journey may have begun as a rescue attempt and took them all over the place?). Within the forest they battle dark creatures and the king's top warrior. I believe the woman magician is taken captive at some point during this.
This is about all the detail I can remember. I read the novel in winter of 2010 and can't say how old it likely was. I was told it was part of a series, and I think the novel ended with at least the warrior character leaving to go on another adventure (can't say if the woman was with him). I also seem to recall there being some sort of a romantic interest between the man and woman.
Any help identifying is appreciated.