put rings of various material around wood then turn to shape? copper rings with white rings some have had turquoise or snake skin like the pen guys do. i dont think they cut the wood into sections because the grain lines up to well
I'm betting they cut the main blank and stack it for different wood species and maybe for the copper. It would be easy to realign the grain pattern when the blank was square. For turquoise and others, I'm betting a turned groove with a filler.
I would cut that blank and insert the white (antler/acrylic/etc). Cutting with a thin bandsaw blade or use a coping saw or scroll saw also are very narrow blades and allow for grain lining to seem seamless. That center oval button, is it on the other side? If so, they drilled and inserted it and with the bubble shape it gets oval shaped. Straight lines at angles when turned become beautiful curved lines. For example, a celtic knot on a pen.
Notice how the 90 and 45 degree lines merge to make a seamless, graceful curve.
Is there a metal rod running through it? I see some type of finish nail type of point at each end. I would bet the white bands are inserts. And soft metals like copper, brass and aluminum can be turned on a wood lathe so are sandwiched inbetween and all CA glued together then turned. There are texturing tools that create random as well as patterns or else it is a bad CA finish (what my students first CA finishes tend to look like!).
You can metal powder I have done so with bronze and brass inthe past. I used CA as the fixative, half fill the groove then apply the CA then dust on more till it sits proud sand to finish. With a little practice you can get a very good result with glue voids.
The bond of the glue between all of the different materials wouldn't be an issue with a shaft of metal running through the handle (which I'm assuming a spear would have). I have a couple of knives my granddad made toward the end of WWII that have handles (grips) made of stacked wood, brass, aluminum, copper, leather, and plastic (poker chips). They are all held together on the shank of the knife, and whatever glue Grandpa Bill used, it's still holding They're not lathe turned - they were shaped on a belt sander, I believe - but a wood lathe could handle all of those materials.