You could also use a triangular file to carefully remove the smooshed part of the the thread. You will need one of the small triangular files. You only need to remove a small amount of material that has been pushed into the area where the mating thread wants to go.

Another way is if you have a spare Campagnolo cone or another 10mm x 26 tpi cone, cut a groove into it the threads on the cone to make it into a die and run it onto the axle. You could also grind a lead-in to the cone so that it cuts more progressively. You would be making a thread die out of the cone.