Just protect that knot when you start going mad scientist on the handle. I use green painters tape when I've had to do work like this in the past. It comes off the badger hair without hurting it at all.
Use it, buy it if you don't have it, don't use whatever you got laying around. I know you wouldn't, but I can just see you wanting to fix the problem ASAP.... Cause that's what I'd be like too.