From looking at your photos, it appears that you have some pitting away from the etching areas. I notice some pitting on the shank, tang, and spine. For your project, you could cheat a little. You could drop down a a 200 or so grit, and then work upwards to remove the scratch marks gradually, on the areas away from the etching. This would improve overall the appearance on the non-etching areas. The lower grits remove pitting deeper and more effectively. Plus, this would be a heck of a lot faster than grinding away at 600.