The rules say to sharpen the cutting edges of shovels and such with a file. But I have a grinding wheel which is just as good and faster, LOL! We're not talking about fine cutlery here.
So, being careful to generally match the grinding angle to the original beveled angles, I set about the crude sharpening. You are only making an edge on one side (chisel, not knife). LOOK at those sparks, LOL! I had the handle of the spade resting on the floor, so the grinding angle stayed very consistent. A light pass back and forth did a wonderful job.
So I took another piece of an old undershirt and simply wiped the tools with it dipped in motor oil. Then I wiped the surfaces of excess oil with a another cloth.