I decided to try the sandpaper method first. I didn't have dowels that were a close enough fit, so used the tools themselves to round over some edges on a piece of cedar, then wrapped 280, 320, and 400 grit sandpaper over the edges and gave end each 10 strokes with each grit. Not perfect, but definitely sharper than they were.
I notice in the pictures that the outer sides of the oval shapes are eased a bit after sharpening, which may be because of human error of not pushing or pulling the tool uniformly side to side. But, I also noticed before sharpening that the tool would leave a slight impression in the workpiece where that outer edge contacted the wood, so maybe that will now be lessened.








