Ivo - the dry human hair is tougher than copper wire of the same diameter - but when wet it is much softer. Hence all the hullabaloo about lather, softening the beard, method shaving etcetera. Of course that can be taken too far, since once saturated, the hair really cannot hold any more water. So beyond a point, all that stuff is just hot air... errr... water... ummm... lather.

And even khukuris are convex ground; I cut myself once on one as sharp as a razor - well - not shave ready straight razor, but say a used DE blade. They are incredibly tough knives too, and at least in Nepal, there is a lot of mystique that surrounds them. Unfortunately they don't yet have the western exposure of the katana, so they are inexpensive.

See http://www.himalayan-imports.com/ for khukuri info.