Vikings were one of the most feared warriors of all time, but only a few of them had the chance to fight with one of the best blades of their era, known as Ulfberht, made of crucible steel. Ulfberht was not one single sword, but a series of medieval swords found in Europe with the +VLFBERHT+ inscription engraved on the blades. Ulfberht swords were durable but also light and flexible, making them a perfect weapon for hand-to-hand combat.

Extremely rare and valuable, they were sought-after weapons for the most elite Vikings. Evidently, the blade was so sharp and the iron so strong that it could easily cut through bones and other cheaper blades, shattering them like glass.
What makes the sword still mysterious today is the thickness and purity of the blade. In the process of forging iron, the ore needed to be heated up to 3,000 degrees Fahrenheit to remove impurities. Considering that Ulfberht swords had almost no impurities and the medieval technology at that time didn’t allow the iron to be heated at such a high level, we still don’t know precisely how blacksmiths forged them. Even today, this quality of the blade is tough to reproduce.