Sharpening a small curved blade.

[asterik216]

I have my grandfather's old times I believe it is. It is definitely old that's for sure. But how ever he would sharpen it has severely put a curve in the blade. He had this knife on him at all times for aa long as I can remember. They only way I can figure to sharpen it and get the whole edge albeit terribly I'd use the edge of the stone. Is that the best way to get it sharp again?

I don't know how to get pics to show up in my post but he is the knife.
http://imgur.com/a/oDUwg

 

[jpm2]

Something narrow like the corner of the stone, rod, etc.
It's an heirloom and the blade is about used up, I would leave it be.