As far as the "Purists" go (I'm not even sure what that would be) the #1 with a single hilt and thumb notches is nothing more than an "improved" #5, Camp and Trail. The thumb nothces are cut into the top cutout, leaving less chance of slippage. The "Crow's beak" prevents the hand from slipping off the back of the knife, making it ideal for trapping muskrat, beaver or mink. I think this Italian guy is way ahead of the curve on this one.
Bravo Guido, Capt. Chris