Most chipper blades can be sharpened easily on a wet stone.
Be sure to you touch up the center point too. Often forgotten, the center point is critical to feed the main blade properly.
A file will do it on the center point. Try to keep the angle true, keep the file flat to the surface of the center point.
I use a black marker to black out the face of the main blade cutting surface...then lay the top edge face down on the wet stone..keeping the angle flat and with a circular motion hone the edge true.
Once all the black from the marker is gone, it's good to do.
Ed "Backwater Eddy" Carlson ~ ~ ><,sUMo,> ~ ><CD