I hone all blades, including utility and exacto blades. Many folks don't sharpen for enough..meaning they never get the two planes of a cutting edge to meet. Magnification of the edge at various stages of sharpening is a great way to explain what is going on during the sharpening process. One of those lit magnifiers may be worth getting. A USB digital microsope
is a really cool teaching aid.
Ideally when you initially sharpen a cutting tool, a wire burr will form. This looks like a little flap of tin foil stuck to the edge and can be moved . When you get to this point you have "sharpened" the metal down to a very thin place along the edge, and it is critical that this foil or wire edge be stropped away, not broken off. Hand stropping takes time ( I use power on some things), and the closer you get to completion, the more apt the wire edge is to break. Once you get to the "magic point" where the two planes of the cutting edge meet, and the wire burr has been worn away by the stropping compound, you are getting a tool that is truly sharp.
A cutting edge is really a kind of saw. The quality of the steel (grain structure) will determine how small you can make the "teeth" at the edge. If you could make an edge achieve a thickness of one molecule, why you'd have a really sharp tool. Edge holding ability comes from hardness and bevel angle. You sharpen the angle based on the use. Typically, a scalpel has a lower included cutting angle than an chisel. Microbeveling is a technique that tricks the tool into a higher degree of sharpenness with more resistence to folding under pressure. Mallet struck woodworking chisels can benefit from microbeveling, where the cutting edge may be 15° included, and the rest of the tool beveled at 20° or more. It's also a fast way to get a lower angle as you have less metal to remove at the edge.
I'm new to use of the round knife, but for some cuts, like an exterior radius on a hide that is particularly firm of hand, I find it indispensable, as I rock around to make the cut. I like a honed utility blade for long straight cuts.
Clean cut leather shines, literally.