I found this information from an article written by J. Clements on the Association for Renaissance Martial Arts (ARMA) site.
http://www.thearma.org/essays/damagededge.htm"When real swords were damaged on their edges, they could, depending upon the severity of the distress, be reground or re-polished to remove the trauma. This would of course require the entire edge of hardened steel be ground down, not just the damaged portion. A blade could only sustain so much of this before the edge’s bevel extended into the softer inner core of sandwiched steel. At this point, an edge of particular sharpness could no longer be maintained."
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"There is no evidence however that damaged blades would be repaired by “reforging.” Ask a qualified bladesmith about “repairing” heavy nicks on knife or sword and you will learn it’s not an easy task and even borders on the impossible. Once the gouges were ground down, the process of reheating a blade to the degree that it would permit working the metal of the edge back into shape to re-welded the chips would still require it being re-tempered and re-hardened afterwards. Doing this would also entail removing the hilt and the whole thing would need to be re-polished. Given all the work this would require the swordsmith might as well make an entirely new blade instead. Small deformations (ductile damage) to the edge of softer steels can actually be cold reformed by light careful hammering. But on edges of harder steel it re-stoned or refilled.
Distinguished swordsmith Paul Champagne notes that in attempting to polish out and reshape a damaged edge in this way will affect the original shape and thus the feel of the weapon: "After a repair at the sword polishers you might barely recognize the feel of your own blade. It's not just grinding out the nicks; you have to reshape the steel to an edge in the damaged area which means having a very abrupt edge bevel or making the sword thinner to accommodate a more gradual entry into the edge. Just 2 nicks only 1/16" deep directly across from each other means making the blade at least 1/8" narrower in that area.…So much for the initial blade design after a couple of repairs." (Personal correspondence with the author, September, 2004)."