Because of what I can only describe as haphazard storage practices on my part (ziploc bags in cardboard boxes with no padding is fine right?), I had two punishers on old Incubi pewter models break off, along with the head of a warscythe on a Necron Lord.
The hafts are so thin that I can't drill and pin them. I know some people can, but I don't have the experience or hardware to do so.
I do, however, have a soldering iron.
It worked surprisingly well. Oddly, GW's pewter has a higher melting point than lead, so I didn't have to worry about melting the models. I did find that the solder didn't want to bind as well as I'd like, so I put a few coats of ultra-fine super glue over top once everything cooled.
There was an unexpected benefit; one of the punisher blades was lost at some point, so I trimmed down and soldered on a spare blade from the old Talos model. It looks pretty slick, I deliberately used a bit too much solder and pulled it away to create a hand guard.
If anybody else finds themselves in a similar predicament, soldering definitely gets the job done.
Worry not about Chaos; it is the used 40k market that shall be thy temptation.