Karda,
It is a lot of work, that's for sure. By minor imperfections in sharpening, I should be clear that I mean a toothy or jagged edge which isn't uniform along its length. An edge will always be uneven when you look close enough at it, however the difference between the sort of edge produced from a file (traditional khukuri method) and the sort of edge produced from for example stropping with a finer abrasive is huge. From what I understand, when chopping wood, a blade edge does not dull from edge wear and abrasion like a typical knife does. Instead the damage comes from impaction and distortion of the edge from the large forces being applied. In this situation, these minor imperfections from sharpening act as stress raisers and places of weakness. From here, these small teeth bend or flatten with impact. This proved a larger area at which the knife edge contacts the wood and the added force leads to tearing, rolling or chipping at the edge dependent on the specific heat treat of the knife. In any case, my understanding and belief is that highly refined, polished edge is ideal in this situation for any given heat treat within reason. The edge is much, much sharper but also keeps that level of sharpness for significantly longer than a knife sharpened with a coarser abrasive. Note that I use the word ideal, as in "the best possible thing" This doesn't necessarily mean that it is the least work or that any other opinion is wrong, it's just how I prefer to keep my chopper edges, because from experience I think it's the best.
As for how it affects the purpose, I understand that it's a tricky one. I'm not claiming that a polished edge automatically means that it is suddenly ground thinner and balanced differently or anything, but simply that the higher sharpness allows the knife to cut through thin, flexible shrubbery in a manner that a knife of lower sharpness can't. In essence, the higher sharpness means that when striking these flexible branches, the knife begins to bite into the material while putting less force on the entire branch. Once the knife has sunk into the wood of the branch and has a hold, the knife does the rest of the work and goes all the way through. A knife with a less sharp edge will impart a lot more force on the initial impact and just push the branch out of the way. I'm sure this is an event that many khukuri users are familiar with.
Hopefully that clears up the reasons for my statement. I know it might not be a popular opinion, but it's mine haha!
Take care,
Andrew
