I’ve found that Black walnut is just about only suitable for arrow nocks...and almost not even those, because my served strings work through them over time. I’m gonna need to burnish all of my walnut nocks.
I’ve had nothing but failures for BW tip overlays...but as handle material BW should work. I would use multiple thin strips of it, as suggested.
Black walnut is gorgeous wood, but it is just so dern brittle.