A replacement hickory hammer or hatchet handle. They really don't weigh much without the steel heads. And unless you baton a sawback knife, should be quite durable. One of my carpenter tricks back in the day was to sink a 16d nail with the handle of my hammer.
Yes, I've done that to. I've pounded long nails into Hickory pick axe handles after working them into a usable shape. A good hiking cane alternative.
The whole notion of carrying a baton and knife seems to appeal to the "baton for fun" crowd more than the bushman. The OP seemed a little stressed with the initial answers but methinks those answers were delivered based on post 1's wording.
Some woodsman just like to go out and "play" using their skills. I've got flint and steel. I've got a tinder box. I've got a ferro rod dangling from my pack, my knife, there's one around my neck. I also have a brass Zippo lighter, full of naphtha in its own belt case. But to be honest I just love to spark up a blaze with the steel on flint. Takes me forever and I try real hard. Now my point is I take the time to cook up some charcloth to put in my tinderbox so why not take the same prerequisite and stick a Bic lighter in my jeans pocket?
The flint is more fun.
That being the case maybe the OP just likes to baton? A LOT of forumites do. Read any WSK Review and it's Baton ability is point number one. Does it cut? Gotta read the WHOLE article to get to that point. Ha! Like an I-phone review, It does this, and this, and this...but does the cell phone make phone calls?
So for the baton afficianados out there a dedicated baton is not as far off a notion as you might imagine.
Head down to the lumber store and pick up a replacement hickory sledge hammer handle. Saw off 16 inches of it. Sand it down real nice. Drill a hole in one end. Paracord it up maybe with wrap and lanyard,
viola'! Instant portable baton.
Now before you backwoodsman bushcrafter wilderness explorers start laughing out loud they sell such a tool on about three different sites I googled. A wonderful 'tool' for this purpose is a 'Tire Checker' that truckers carry. They sell em at truck stops across the country
From a different angle. Bass Pro Shops sells a fish billy to knock your fish out. True story. All these would serve the OP'S purpose.
We who live in the woods with the woods have a saying,
"'The only stupid question is the one not asked."
The goal is to learn here, isn't it fellas. Trust me, there's subforums here where that is NOT the goal. Ugh...
