I'd just use superglue and try to be careful to keep it towards the outer edge of the handle. You can sand it off the outside with high grit sandpaper, but you can't undo any damage it might do to the knot if it soaks into the hairs.
If the knot is loose, you might even want to remove it, repair the handle and then remount it.
Artisan Brush recommendations???Looks like you are going to have a nice artisan brush with a great knot.
Artisan Brush recommendations???
Send it back to Simpsons. You might be surprised about the miracles they can work for not too much money.
Rudy was my first thought.Bob Quinn - Elite razors
Rudy Vey - Ultimate pen designs
Both are members/vendors on this forum.