Stole this idea from coach, thanks coach. IIRC coach took his handle down further than I did. I did not hate these handles as so many did, but I really liked coach's pictures so I tried it myself.
I used a sandpaper progression of 80, 100, 220, 3?0 (can't recall), 400. I sanded until the grain was smoothed out. I did not try to significantly decrease the diameter of the handle, I just did not like the exaggerated hills and valleys of the grain.
The outcome is smoother to the touch, which I like. It feels...more quality. Aesthetically the contrast between the dark finished that remained and the lighter wood that was exposed below is very cool, IMO.