It is a science fiction/fantasy novel set on some world that isn't earth. I think it is either in the future or an alternate universe. I read it in high school or college so, 10-17 years ago.
There is a female mercenary who is part of a mercenary guild. I feel like I recall she was being pursued by guild members who were trying to hunt her down. I'm not sure if there is any more to the story, but I remember that she was assigned to a mission and that she was able to grown iron nails.
Sound familiar to anyone? I want to read the book but have no idea what the title is or who it is by.