More than 2,000 swords have been found so far from the viking age (around 800 AD - 1050 AD). However, unlike most of the swords that were made for battle, recent discoveries through the use of neutron scans have proven that some of these swords may have been purely created for decorative purposes.
All three of these swords (found in Denmark and pictured above) were made through pattern welding which includes using thin strips of various metals, irons and steel. They are then welded together, folded and/or twisted and then forged in various ways to produce decorative patterns.
Whereas swords made for battle were typically made of pure steel.
Learn more at: http://www.livescience.com/58654-viking-sword-scans-reveal-norse-culture.html