Taken in context, I think that the togishi are referring not to one or two polishings done by a single craftsman, but repairs done over centuries. They make mention of the fact that 800 year old examples were swords that had not seen much use or combat.
When I get done sharpening (more properly, polishing) my hands are covered with swarf and the container I use to soak stones has a grayish silt on the bottom. And that's after polishing only a few knives in an afternoon. If, theoretically, you collected the swarf from all of my relatives going back several hundred years it amounts to quite a bit of metal.
I have also noticed that softer metals "bleed through" the decorative surfaces of modern kitchen gyuto knives. In fact, I used to keep a small bottle of soft soap and canola oil in my kit. When a knife showed telltale orange spots, I would slice off a piece of a carrot and polish off the spots. I was trying to stay ahead of severe rust problems on knives that were used for long shifts and usually always wet.
But my point is this. Folded steel isn't uniform in its layers. It's hammered, it wears, I polish it. Even on new knives I find spots of "foil" along the edge from delaminating.
The numerous layers are very thin. The one thing I do know from not only my daily work but also from study is that folded steel knives were always being repaired and "appraised." In short, it appears that all who value this type of cutting implement are
very worried about its care.
Admittedly, my observations are anecdotal. But even I notice the wear and the ever changing complexion of individual knives. And I use very fine grit waterstones and I'm known for having a soft or very 'slow' hand. (Below is an example of a knife made from 1095.)
I believe that the sharpest knife this world has ever seen is the yanagiba. Traditional 'blue' or 'white' steel can show rust in a matter of hours. The rust is always being removed and the edges need to be polished. Literally, I'm grinding away the very thing I respect.
