If the handle is metal it will be either aluminium or magnesium. Most aluminium alloys can be welded but it requires special equipment. As far as I know magnesium can't be welded, and trying to do so would be quite dangerous (if you haven't seen burning magnesium, you can't even imagine the temperature and intensity - that is what military "starshells" and other parachute flares consist of). I suggest you think about getting a second hand handle rather than repairing the broken one. Glue will not help - the original handle broke because it was overloaded in some way, and the metal was a great deal stronger than glue.
