I agree that it doesn't look like a modern ice auger, but this tool appears to be quite old and I figured that they were made much simpler years ago. Have you seen many of them as old as this one?
It looks like it could be used for either purpose, but I'm leaning towards ice auger mostly because of the angle of the blades, the fact that there are two of them, and it seems to me that it would would work well for shaving ice.
I haven't been able to find any other tools yet that look like this one, but I'll do a little more research this weekend.
Rob