The trick in all this is once you get it sharp, keep it that way. Sort of like a professional meat cutter steeling a knife all the time. Keep one of those round stones in your pocket. When you feel the edge starting to dull, spit on the stone and touch up the edge. You won't have to grind/file so often.
Dull axes are much more dangerous than you might think. My grandfather was a lumberjack and you could just about shave with his limbing axes.
