Viking swords were pattern welded, a method by which the sword was made stronger. When the sword was made, steel rods were twisted together into cables. The rods would consist of high quality steel, and lower quality carbon steel giving the sword flexibility when used, yet still able to keep a sharp edge. These cables were then pounded flat, and shaped into the sword. The method is called pattern welding because when the sword was completed, you could see the pattern of the welds of the cables in the blade.

BTW, I was wondering if anyone has any reproductions made this way, and how they stand up to other swords?

Far heil!
Icel