I think much of the older ideas on this subject are being overwritten, but with a hefty grant one could compare trace element analyses of metal and slag inclusions (via non-invasive XRF or similar) between swords and smelting sites, and get a rather definitive answer.
These two papers are just the tip of the current research iceberg:
Indigenous and imported Viking Age weapons in Norway, a problem with European implications
Martens, Irmelin
http://www.archaeometry.dk/Jern/Mart...plications.pdf
The Vlfberht sword blades reevaluated
ANNE STALSBERG
http://jenny-rita.org/Annestamanus.pdf