I did some serious damage to the edge of a bowie some years ago by discovering a flint inside some wood I was splitting (Don't ask me how on earth it ever got there!) All I did was to "over-do" the sharpening every time the knife needed it. By sharpening the blade twice as much as it really needed each time the nicks soon became virtually un-noticeable and disappeared altogether after about 3 years. Shing has it right in my opinion. If the knife is worth keeping and still does what you need of it despite the nicks, there seems little point in grinding a lot of steel away to get back to a smooth edge other than for purely aesthetic reasons. Damned annoying when you do this to a favourite knife though.