Sunspear — J. Michael Robertson

A thousand years have passed since the Sunspear, an ancient weapon forged by the Gods, was lost to the sight of men in the last great battle of the Raven Wars. Now, the Dark God again reaches out from the Land of Eternal shadow to touch the world with his evil. The Goddess Danu gives Ciaran, a young Celtae warrior powerful in the Psi, the vast psionic power of the subconscious mind, the quest of finding the Sunspear. If he fails, the Dark Gods Long Night will fall over the world forever.
The quest leads him ever deeper into the Forbidden Lands, perilous realm of the Shadow, where he is pursued by the Dark Gods evil Ring Lords, who also search for the Sunspear. The Ring Lords, however, are not Ciarns only worry. The Dark God sends one of his First Born, a Shadhul mind-slayer, into the world to capture him and bring him to the Stone of Tears where he will either accept the Dark God as his Master or be cast into the Well of Souls. As he strives to elude the Shadow Lords hunters, Ciarn must confront his forbidden love of Danus tiny priestess, RILLSONG. He is further assailed with guilt over his infatuation with the beautiful Shadow Druidess, ISNGEL who captures his beloved foster sister KIARA and gives her to the Ring Lords.
In the Valley of the Gods, he rescues Isngel and her half-Elven Ahati warriors from the deadly, Halfsouled Draugr. Joining forces, they fight their way through hordes of the near-immortal beings to reach the lost city of Gorias where Ciarn claims the Sunspear. Using the ancient weapons god-like power, he destroys the Ring Lords army that pursued him to Gorias, killing thousands of warriors, and laughing as their dying screams fill his ears. Only then does he realize that the greatest evil he has to overcome is not the Dark God, but the darkness that dwells within him. He must both learn to use the enormous power of the Sunspear wisely and keep his Darksoul at bay. If it gains control, he will become a creature of shadow, a Soultaken.