I was wandering through the internets and happened across a style of axe used in Portugal by those harvesting cork from cork oak trees.  It'd be an interesting project so got a little attention.

Looking closer, however, I noticed a wedge system to attach the handle which I hadn't seen before.  It appears that they use a 3 wedge system in an equilateral  triangle to expand the handle and keep it in place.  By my take, it allows for a round drift (easy) with even pressures around the whole perimeter of the eye. 

Got me to thinking about wedge systems in general.  To the best of my memory in the US, I've only seen single and double parallel wedges used--probably for economy.  It's actually a pretty lousy system as it tightens in the exact wrong direction:  If you are only using one wedge line, it'd seem to me you'd want to keep it tightest in the line of force rather than side to side.  I've had single wedge tools loosen up in that line as they wear, even if you tighten the wedges to apply the usual side to side pressures.  The problem is, a wedge split the other way is likely going to increase handle splits when used.

Is there such a thing as the ultimate/better/best wedge system?  Something that stands out above average?  Just curious to see if someone's run across something that they felt was outstanding or unusual (eye-catching).

The traditional Japanese style caught my eye.....

The pickaxe style handle is self wedging but it's not as pretty.

Hollow round wedges are excellent because they spread in all directions.  The problem with all wood handle wedges is that they're driven into end grain which has little holding strength compared to side grain.

Of course you could go "belt and suspenders" by making the hollow round wedge long enough that you could cross drill the head, wedge, and handle to rivet/bolt/ screw the whole shebang together.

The flip side of all of that, is that the better fastened the handle is, the harder it will be to replace should the handle break.