I admit that this is my superstition.
A good knife is all about the condition of the edge. A knife's good (expensive) edge is about two things, i.e. quality of the metal and proper hardening and tempering of the edge. A commercial knife sharpener uses mostly motorized grinding stones and belt sanders. Both tools require the best skills and patience. It takes very little time to remove too much metal and it takes a fraction of a second to de-temper the best edge and permanently damage the knife.
I use water and sharpening stones and lots of patience to sharpen my knives.
dcarch