Yes, seriously. I picked up about 30 pounds of obsidian on a recent outing, to learn knapping.

I bet there were a lot of wielders' hands sliced early in the days of the dagger, if they were sharp enough to slice.

They were certainly sharp enough to slice. Obsidian and flint cutting edges are equal to, or better than, modern surgical tools (until they wear down in use, which happens fast because they're delicate). I haven't made myself a copper knife yet, but I have experimentally taken a sheet of copper and pounded an edge onto it (using two rocks); not as sharp as my modern steel belt knife, but still readily capable of slicing flesh.

Evo, a word of caution if you didn't know this already: Once you start knapping, keep track of all the debris you're making. Every piece you knock off is a razor-edged disaster in the waiting! Most knappers seem to work over a leather ground cloth, and at the end of the session dump the debris into a bury pit to keep it out of the way.