Glen Cook 
Swordbearer 

A young boys dreams of glory and war turn into a bitter nightmare as his fathers kingdom is overrun by an invading army. Lost and alone in the woods, he finds an ancient sword that promises him the ability to claim his vengeance. As he begins to take that vengeance, he comes to realize the price that the sword will demand of him. Enemies soon become allies and strange bedfellows abound as the prophesies of an age swirl into chaos.