You're only touching the very edge. When I have the time, I'll get out the strop and compound, but for a quick touch up, a ceramic rod works just fine. Just use very light pressure and only touch the very edge at 20 to 30 degrees. You can come back later and round it off with a strop when you have the time. The rod is quicker. People worry too much. Sharp is sharp. Who cares if it is convex or straight? Now a full convex grind works great for choppers because there is less resistance when chopping through a target, and less problems sticking in the wood. But even those I touch up with a ceramic rod.