Hi, I'm being a guest. I am in a lesson at the moment, but I'm very bored.
Dude, it's a stick. When you say things like "negative dihedral", you actually do get me confused. I know that the stick needs certain things: a weightier end, a slight bevel and a basically aerodynamic shape. Beyond that, I don't know, but what I do know is that I can hit something with enough power to at least stun or if not then kill an animal, at about twenty or maybe even thirty yards. The curve is important, but not actually essential, but the weightier head is very important. It will flutter otherwise. Maybe the problem is that you are thinking too much about the problem.
I sound a bit like a dunce at the moment. Sorry mammothunter.
If you want a stick that can kill something easily, and is easily made, then go for a regular, straight stick, and carve down so you end up with a "potato-masher" shape. It's good to leave the bark on the "head." They fly far and hit hard. And that is what is important, above all else, even aesthetics.