My suggestion is that you take a normal spade/fork/etc. and cut the handle
directly in half. Obtain some strong metal (probably steel) tubing and drill a
couple of holes at each end. The tube should be a snug fit round the two shaft
ends.

Now, place the two ends of the shaft into the metal tube and adjust till a
comfortable 'fit' is achieved (for you, not the shaft/tubing). Once this is
achieved, screw screws through the holes and into the shaft.

I think this should work. Please let me know if it does/doesn't so that I know
if I should patent the idea, or just go and boil my head.

All the best,

Dave.