Ripping 8/4 walnut. A good rip saw comes in handy for jobs like this.

Rough shaft. I planed this down to smooth and square with a #7 plane. All said and done, it ended up about 3/4" x 1 1/2" at the top and it tapers down to 3/4" by 3/4" at the bottom.

Marking out a rough design for the handle.

Made relief cuts. What I learned is that you want to make sure to make a cut right at the apex of your arc. That's where the grain changes direction relative to the cut you're making so when you come back with the chisel, if you have not made a relief cut at that point, you'll end up splitting off more wood than you want.

Some very careful chisel work. Not shown: the first try that split all the way through and now lives in the trash.

After some more careful chisel work and a little rough rasping.

After about 30 minutes of some finer rasp work and some filing.

On to the shaft. I hit the corners with a #4 smoothing plane to get the rounding started. I decided to keep the rectangular shape but round the corners quite a bit.

After that, I hit the corners at various angles with the spokeshave. This job could be done exclusively with the #4 or the spokeshave or even a rasp.

Boring the hole for the dowel joint. The handle got the same treatment.

Weirdest glue up ever. None of these are very tight, just enough to keep the handle seated firmly.

To finish, I went through sand paper grits from 100 to 150 to 220.

Then I used my own Danish oil recipe, nothing complicated. 1/3 Mineral Spirits, 1/3 Boiled Linseed Oil, and 1/3 Polyeurethane.

It got a few coats of this at first to soak the wood, then a few more with a bit of sanding at 500 grit in between. Depending on how it dries up after several days, it might get more of this finish.