Hi Terry,

I don't have any handy to doubt check, but i think most are saber or double bevel.
A normal stone or sharpmaker works. I use a sharpmaker on most of my blades, however I did reprofile my DF to a convex edge on a belt sander.

Regardless of the edge, I usually finish with a few light passes on a strop loaded with .5 micron veritas green.