: Compared to typical iron or pattern-welded blades of the Viking Age, Ulfberht swords were incredibly strong, flexible, and sharp, allowing them to slice through mail armor without shattering.

The phrase is also popular in modern gaming and fiction to describe "illegal" or overpowered weapons:

: On collector forums like the Nihonto Message Board , it is often used for modern Chinese fakes that mimic Japanese signatures but lack the correct historical construction.

: Players use the term for "illegal" legendary items like the Soulcatcher Blade , which summons hostile mobs to fight for the user, or "God Swords" with impossible enchantment levels (e.g., Sharpness 1000).

: They were crafted using crucible steel , a high-purity metal with a carbon content so high that the technology to create it wasn't thought to exist in Europe until the Industrial Revolution.

The Sword That Shouldn't Exist -

: Compared to typical iron or pattern-welded blades of the Viking Age, Ulfberht swords were incredibly strong, flexible, and sharp, allowing them to slice through mail armor without shattering.

The phrase is also popular in modern gaming and fiction to describe "illegal" or overpowered weapons: The Sword That Shouldn't Exist

: On collector forums like the Nihonto Message Board , it is often used for modern Chinese fakes that mimic Japanese signatures but lack the correct historical construction. : Compared to typical iron or pattern-welded blades

: Players use the term for "illegal" legendary items like the Soulcatcher Blade , which summons hostile mobs to fight for the user, or "God Swords" with impossible enchantment levels (e.g., Sharpness 1000). : They were crafted using crucible steel ,

: They were crafted using crucible steel , a high-purity metal with a carbon content so high that the technology to create it wasn't thought to exist in Europe until the Industrial Revolution.