You could fill the body with Bondo and sand the broken edge flat. Then turn the brush upside down and insert the knot on the other end...it would be a small knot, but it would salvage your work...but obviously you would have to refinish the whole thingToday i learnt a valuable lesson. I wish i could learn lessons on wood i had more of and handles i didn't like.. ah well, there's a lesson in that as well.
I wanted to expand the hole of this stubby to accommodate a larger knot as i felt the handle was more suited to something bigger than the 26mm i'd drilled it for. Turns out thats not quite as straight forward as i'd assumed and this destruction was the result.
Very sad today. I was happy with that little stubby.