In terms of using the billhook, why don't you put it through its paces chopping and splitting and let us know how it performs. I can see that specialist tools and techniques may be an issue for lefties but, as a billhook user for scrub clearance, trimming and firewood preparation (very limited requirements I know) I'm struggling at the moment to see what difference it might make....
One thing I can think of, concerning the bevel on the blade is, depending on the swing. If you are chopping across a branch or a sapling, for instance, if the bevel has the angle facing >>> away from you, it could possibly glance off. If the flat is oriented >>>to the outside edge, then it bites well, essentially grabbing and biting with every stroke. Driving the edge into the piece. Imagine a chisel. You want the flat side to contact the surface first.
I earn my way cutting timber and a machete is the tool I use for clearing out around the base of trees.
Over the years, I've bought a few that weren't sharpened true and the bevel went to one side or the other(these days I don't use it unless I've set the bevel to my liking) If the flat side faces you when you hold it, facing down in your hand, if you aren't careful you can deliver a strike and if the edge doesn't bite well it just debarks a limb or sapling and skids off <<< *in your direction*
I use corn knives(place my own handle on it) and all of them are generally sharpened to one side only. They've got good weight and are thicker than a common machete. The first few times I ran across this if I hadn't been on my toes I might have lost a knee cap, shin or calf etc... I always center the bevel and make fairly slim edge. I need to chop in all directions and angles as I clear around around the base of the tree. And also my escape route through briar's and such if the tree decides it wants to kill me too, and I need to get away. A centered edge is preferable for my needs.
I've always wanted a billhook(they aren't popular here for some reason) and was never aware of them being beveled to one side or another. It seems a bit of time spent could center the edge and there wouldn't be much of a problem at all.
my two cents
