I make my blades with pretty big barbs, i use a a 4 inch cut off wheel to get the basic shape, use a grinding wheel to refine it then go at it with a hand file and dremel.
With the size you are using i'd suggest a dremel. If it's meant for actual gutting you will want to have the inner portions of that hook to have more space than the entrance, why not use a drill to make a hole then cut a "entrance" slot into the hole, then sherpen the inside edges of the hole?
That way you will have a very small opening area (for safety) but the hole will provide a large cutting area to open up the hide. This will also be of use for cror and chutwe lines as well.
As a note the edges of the entrance to the hole should be rounded.