I do like the idea of checking the edge with under a microscope, but, I'm not sure if you will need a 400x or more microscope. Steel has its limits, and you can see them at 50x. With 2000 magnification, if you look straight at the edge, it looks flat, not sharp, no matter the abrasive material you use. For broken glass, you might be able to see for edge a line of single molecules, but for steel, that's as fine as it can get...