I inherited a reasonably good set of kitchen knives along with a knife "steel" (rod with file-like toothed surface). I can get a pretty good cutting edge on the blades (I'm still working on my sharpening technique), but I don't quite understand the steel. I've read up on it's use, but when I try to "touch up" an edge prior to use, I usually end up dulling it further.

My main question is: Why do the majority of these things have a rounded taper? Seems to me that the taper makes it more difficult to maintain a consistent angle. Anyone have any insight on this?