The chisel edge is derived from the Japanese tanto style stickers. The point and edge are designed for penetrating metal armor. Deciding how coarse or fine a grit to start with depends on the condition of the edge: if it's very, very dull or nicked, start at a very coarse (100) mesh level.
If you will go to a sushi resturant and ask how it should be sharpened, what I think they will tell you is this: keeping the beve itself perfectly flat on a medium (600 mesh) stone or silicon carbide paper and honing oil (not 3in-1 or motor oil, but mineral oil will work ok too). Laying the paper on a mousepad on the kitchen table or counter is just fine. Make 15 strokes away from you with a motion as though you were going to slice the stone or paper, like a curveball acts. After 15 strokes on the bevel itself, then turn it over and make 1 (one) stroke on the back toward you. Repeat twice.
If there is no improvement, you may need to reduce the mesh (fineness) of the stone or paper. Do it a 400 mesh, if no good, drop to 200. Once you get to a grit that produces a ncie clean edge that reflects no ligh on the cutting edge itself, then work your way up through the grits to at least 1000 mesh. Silicon carbide paper is cheap, and it can be purchased at auto body repair supply stores up to and inclucing 2500 grit (mesh).
This is a triial and error process, and the more you practice, the better you'll get. Blackie Collins is one of the most respected makers and designers in the "knife world". His products are carried and used by thousands in the armed forces, and many more in the civilian world. His name has never been linked to a low quality product, at least that I am aware of.
Dr. K is quite correct, as are the others about sharpness. First is that this is principally an emergency or life-saving tool: it cannot be too sharp. The sharper the better. Straight razor or even scalpel sharp is the goal. It must cut without hesitation when used, and not require two tries. If it'll shave the hair off your forearm, then you're there. Second is that a dull edge requries excessive force, and when it does slip, as it surely will at some time, any body part in the way is going to be seriously cut, not because of the sharpness of the edge but becasue of the force behind it. Then you'll need Dr. K or one his colleagues to fix you up. Now, keep your wits about you, and go have fun!
an old River Rat
