If you have a Fomorian King with Water, then you *definitively* do not want to craft a Wraith Sword for him. You want a FrostBran for him, and even with zero water gems, you'll get ahead by first alchemising the death-gems to water-gems... Why would you want to lose the shield on Fomorian King so that you could be wielding an inferior weapon?
That already tells just how bad the Wraith Sword is. Never seen one used by a player under Dom3 (but there are other things I never see which others think are common, so that doesn't prove anything
).