Unky
To space the file work evenly try this:
Take a sharpie marker and draw a line across the pommel cap. Now draw a bisecting line, making a cross. Next, bisect the four quadrants. This will give you an eight fold symmetry.
File a small notch at each line with a square file, and then use a round file to open it up. Go to a half round and make the scallops connect.
For a six fold symmetry with a little extra file work, try this:
Mark the diameter of the pommel with a compass. Walk it around the circumference , making six marks. It should end up where it started, but adjust the marks if needed. Make a mark between the six axis marks. Make a small notch on each of the twelve spots.
Now, every other notch gets filed with a tri-square making a "V", and the alternating six get filed as scallops. This will give you six scallops spaced by six small valleys. Carry the scallops up onto the pommel top a bit, with the valleys filling the space between.