Some Vikings stung by fake swords

"Buyer Beware" is an ages-old concept, one that was even true for Viking purchasers of "designer swords." Dr Alan Williams, an archaeometallurgist and consultant to the Wallace Collection, discusses the problems some Norseman encountered when commissioning new weapons.

From the article:

Some Viking swords were among the best ever made, still fearsome weapons after a millennium. The legendary swords found at Viking sites across northern Europe bear the maker's name, Ulfberht, in raised letters at the hilt end. Puzzlingly, so do the worst ones, found in fragments on battle sites or in graves.

The Vikings would have found it impossible to tell the difference when they bought a newly forged sword: both would have looked identical, and had razor sharp blades. The difference would have only emerged in use, often fatally.