I doubt you'll damage the handle. I have 2 that I am restoring. IIRC, the knot of the first one just about "popped" out with no problems. The newest one I have...I don't think I'll be that lucky. I thought about doing a boiling water trick also. But, I was concerned that it wouldn't do anything!
I don't think you'll damage it by any means. My #4 was not as luck as joshgambits. I had to drill, drill, drill to get that sucker out. I believe I got lucky as just before my drill bit went thru the knot it broke loose and I was able to reverse my drill bit and unscrew the whole knot assembly.