Tests at the Wallace Collection reveal that the best Viking swords bore the name Ulfberht, apparently a Franconian name. Franconia has moved in the past 1000 years, though, so this may even have been in Solingen. Many museums have fake Viking swords of about the same age as the good ones, but made of inferior steel because the Russians were blocking the trade route (a familiar story). The Viking Rune writes:

The tests show that high quality steel of the Ulfberht swords is from the mines on the territory of modern Afghanistan and Iran. However, in the 11th century the trade route was blocked by Russians and the supply of steel with high carbon content ended. The demand was huge and soon low quality fakes flooded the Scandinavian market. In outward appearance they were identical to genuine Ulfberhts and their blades were very sharp. Nevertheless, due to the fact that the carbon content of the steel from which they were forged had only a third of the same in genuine high quality swords, they could fatally disserve Vikings who bought them.

The main area where the swords were found was further north, along the Baltic coast and in Scandinavia, so it is suggested that the name Ulfberht may simply have been an invented brand name rather than the name of the maker, and the fake swords an early form of brand piracy.

Markenfälschung schon im Mittelalter.

Ulfberht makes me think of Dilbert, Dogbert and Catbert.

This was reported by the Guardian in December 2008, but has now filtered through to Spiegel Online.

(Via IPKat).