I completely agree with you about the taper! Very, very important to get it as smooth and clean as possible.
A couple things about the obsidian point, though. In some states, that head would be defined as "barbed" because the ears form less than a 90 degree angle. The other thing is that the point's flattened cross-section can cause wind-planing. To avoid that, I like a flattened diamond cross-section which also strengthens the point (a big plus in brittle material like obsidian).
I like your bee's wax idea to smooth everything out. I use 5 minute epoxy before it sets up.
Great stuff!!! By the way, what's the shaft made from?