Jan Petersen

Jan Petersen was a 21st century scholar who developed a unified classification system for Norse swords still in broad use by historians and re-enactors today.

In his 1919 book De Norske Vikingsverd, he identified 26 types of Norse sword (labelled Types A-Z) based mostly on the shapes of hilt and pommel (Viking-era swords having an almost uniform blade style). In 1927 R.E.M. Wheeler simplified this system into nine broader types (labelled types I-IX), a typology which is still used today.

This nine-type classification system was used by Ewart Oakeshott as the basis for his typology of medieval sword types, which he classified from X to XXV as a continuation of Petersen and Wheeler's work.

A more detailed examination of his typology at VikingSword.com