Ace; There is a quick way to weld up a thrower. Get a two to three inch piece of steel pipe of the proper diameter for your intended handle. You might form it to an egg shape. Then weld a blade to this ferule you formed from the pipe. Not the historically correct procedure, but for something you are willing to throw away - frequently, it'll do.
If you want to make an historically correct tomahawk sheath, I saw a good one in a book of buckskinning stuff. It was carried by a USA General in the war of 1812. Two "D" shaped pieces of leather about 7-8 inches across, and about 6 inches deep. Rivet in between the two large pieces, thick leather fillets the shape of the 'hawk. Sew the points of the "D" together with a shoulder strap between the points. Finally, punch holes every 1/2 inch or so around the circumference except where the handle comes down, and use long leather thongs looped in each pair of holes, and knotted with the ends of the thongs hanging down to form a long fringe.