A grinder is great I find for removing a lot of material quickly but be very careful of overheating the steel ruining the temper. I use a 1" belt sander that I picked up for about 60$ and have everything from 80grit for fast removal to 400grit belts for finer polishing but I always finish off with 800 to 1200grit wet/dry sandpaper and a few hours of sanding to bring out the final shine.

*tip* Keep a pail or cup of water near you as you work and dunk the piece repeatedly as your working to keep the heat down.