jimhelm, if you will excuse me, "honed" is not the right term though you use it in context. A metal blade can be honed, that is sharpened on a stone or strop to keen edge. Obsidian blades for scalpels are not "sharpened" this way. They're produced by knapping, knocking flakes from a larger piece. The flakes produced are the finished product for scalpel blades, at least as far as the edge processing is concerned. Obsidian is much like glass, and the edge of a broken piece of glass is already as sharp as it's going to get, it can't be honed sharper than a clean fracture.
interesting link I found that made me think of Perry Winkle:
http://www.theperfectedge.com/howto.shtml
and one for footfootfoot:
http://en.wikipedia.org/wiki/Don_Crabtree