I have had mine sharpened by the guy that comes to Joann's and sharpens scissors. He did a great job and it was about $8.
Foil works a bit. It doesn't last long, but it is a good stop gap measure.
Oh, I use them to trim off the excess batting and backing after I sew on the binding to the front, but before I stitch it to the back. The pinked edge fills out the binding without being too hard. I like the soft edge it creates.