Can someone explain, or point me in the direction of a resource that explains the thinking behind using a wider angle to sharpen a knife that has a narrower factory edge. For example, I had read elsewhere that it was recommended when using the Spyderco Sharpmaker to sharpen a Leatherman blade, to sharpen at 40 instead of 30 degrees despite the fact that leatherman has a factory edge of 32 degrees total. Equally i was given advice in these forums to sharpen my Endura 4 at 40 degrees also despite the fact it comes with a 30 degree factory edge. I am sure there is a good and logical explanation for it beyond peoples preference for an angle to sharpen at. I can't help but think that sharpening at a wider angle than the factory edge will result in eventually rounding of the apex of the blade?