it does look a lot like a beaver tail knife, they were popular with some native american tribes, i seem to recall that the french supplied a lot of the blades.
sheep shears are made of excellent steel as they need to stand up to a lot of abuse while staying sharp, they lend themselves to conversion into knives of differing configurations, as shown in the link i provided. (each shear makes two knives too!) the unusual tang makes them a very distinctive style when you know what they are. crazycrow has a kit for making your own beaver tail knife, or if you are so inclined, you can buy a sheep shear via ebay and experiment, i'd suggest specifying the non-offset style shear.
