You've already got Winter's Fury. By the time you can afford SoZ, why wouldn't you just get Swiftwind at that point? You're going to want to do the legwork for your Epic regardless at some point. Winter's Fury or Wurmslayer would make a good placeholder after that, at least until you can get Earthcaller.
But if you really want to spend that much on a weapon, I'd recommend Blade of Carnage before SoZ.
https://wiki.project1999.com/Blade_of_Carnage