Who said they're the greatest weapons of all time?
Frostmourne is surely one, and Shadowmourne is crafted to beat it.
Hell, we are even picking up shards of Frostmourne to make these weapons for unholy and frost, and yet we built an axe forever ago that can stand with it's full self?
Lore and logic holes ftw!
The Warglaives literally have the same backstory as the Scythe for blood dks. We picked them off some great demon (illidan did originally), and yet here we are.