Those look like wedges to me rather than cut nails; and yes, I agree that it looks to be a shingle/shake tool.
I used to do some wood roofing when I was young; most of our cedar shingles and shakes came from Canada. The saws they used cut these from didn't have many safety guards and now and then you would find a bunch of bloody shingles in a bundle.
I think there are a fair amount of the guys that cut these back in the day that wound up a little short on fingers.
As a matter of fact possibly some of your pointed examples may actually be hammers for slate roofing with the little points. Back in the day when slate roofs were more common the slates were applied when still wet and you could put the holes in fresh slate shingles by using the pointy end.