I roughed them out using a 1" belt sander and a coping saw. Next I sanded increasing the grit until I hit 2000. I buffed them with a jewelers wheel and a dremel after that. They were pretty sharp at that point, but I wasn't sure of the angle on the edge, so I just ran them over my sharpening stones like I would any other blade. They didn't need as many passes though because they aren't quite as hard as steel. After that they'd take hair off my arm, so I figured I wasn't gonna get them much sharper than that.
A word to the wise, don't breathe the dust from shells!!! There is a specific allergy that about half of the population has that is caused by inhaling shell dust. Unfortunately I found out I have it the hard way. I was deathly ill for three days, with constant coughing/mucus, fever, chills/shivers, and horrible joint pain. It was worse than any flu I've ever had. I'm really cautious now and won't even work on shell in the house and never w/o a mask on.