Beautiful, but it's missing a detail ....
A brass or copper ferrule around where the shaft enters the body of the handle would be a great assistance in keeping the handle from splitting in case of excessive force applied to the tool laterally. It's probably not absolutely necessary, but it's something people will look at and comment on ... that it's missing.
On my custom made tool handles (only have 2 prototypes at the moment, turned from poplar), I cut grooves similar to yours, but in them I inlaid some copper wire that I had laying about. The effect was pretty nice. I still haven't finished them yet, because at the time I was under the illusion that I could have a 4-jaw chuck for less than 100 dollars.
Before all is said and done, I'ld like to make my finished tool handles out of Western Redwood Cedar, American Walnut, and Maple. All are commonly available here and are beautiful woods to work with. This way, I can reach for red, brown, and white handles, and generally know what I'm grabbing before I see the tool tip.
