In a scholarly paper, an abstract of which was published recently at Medievalists.net, K.F. Werner examines techniques for forging Frankish swords from 700-1000 CE. Werner disputes the generally-accepted techniques.
From the abstract:
Referring to Anstee and Biek’s ground breaking article H.R. Ellis Davidson posits in The Sword in Anglo-Saxon England a method for forging pattern-welded weapons requiring a skilled sword smith plus two helpers 73.5 hours to produce a single sword. If they are correct, almost twenty years would be required for ten smiths plus assistants working full time to produce just the swords needed for 5,000 heavily armed warriors in Charlemagne’s army (the estimated number of warriors he could put in the field at the time she wrote).
Since this book, K.F. Werner and others have estimated his total forces at 30,000 (and, thus, 6.66 million man hours in sword forging). The proposed fabrication procedures are thus seen by the authors as too costly and time consuming. On the strength of initial results, a sword blade will be constructed by other simpler methods, more likely employed in the Middle Ages, which these eliminate numerous time consuming welds that could only be performed by a master craftsman. The method that we propose could provide a better explanation of mediaeval-sword forging than currently exists.
The full text of the article is also available online.