The undead fear life just as the living fear death. It is not unusual for a sentient undead being to completely destroy all remnants of his or her previous life after having turned. Unfortunately, in order to create an artifact capable of reverting Ras Frostwhisper to a mortal, we must have a keepsake from his years among the living. You must venture to the ruined city of Stromgarde, Frostwhisper's home, and search for such an item. May luck be with you, adventurer.