I have one of those wine bottle foil-cutters. It was a freebie with something or other, not sure what. Completely useless; I always use the tip of the corkscrew to prise/peel off the top of the foil before taking the cork out.
I had no idea such a thing existed. I have a corkscrew with a small knife in it, but I didn't know they sold foil-cutters as a separate tool.