The Sunrise Lands — S.M. Stirling

Young Rudi Mackenzie has grown up knowing that he will one day assume leadership over the Western Oregon survivors of the technological disaster called the Change. But a prophecy made at his birth spoke of an even greater destiny--a destiny that is about to be fulfilled.

A mysterious traveler has arrived in the Willamette Valley. He brings news from the East, from Nantucket Island, long rumored to be the source of the Change. He has been sent on a mission to bring back with him the Sword of the Lady from the sunset oceans.

As son of the High Priestess, Rudi is the Sword of the Lady. Now, guided by the traveler, he sets out on a quest across the Changed land that was once America. But between Rudi and his destiny lies the Valley of Paradise...and the cult of a madman determined to stop him.