Hi cornelistromp,
I cannot believe that nobody has responded to your thread so far, so I feel kind of obliged to leave my favorite field and have a go at this.
Viking? NO WAY.
It's the fragment of a South German ca. 1535 Landsknecht backsword. Look at the pommel. The quillons are missing as well as the wooden cord bound and leather or velvet covered grip.
I attach images of a similar pommel of a contemporary Landsknecht dagger sold at Bonhams in spring, and of a sword sold at Christie's.
For lots of more illustrations, please see my former thread on Katzbalgers and related Landsknecht swords:
http://www.vikingsword.com/vb/showth...ght=katzbalger
Best,
Michael