Instructables has instructions on how to integrate a $20 battery powered soldering iron into a $16 airsoft pistol. The battery is integrated into the magazine, allowing fast reloads.

I hate the ergonomics of pen-shaped soldering irons. Just this weekend I gave myself a decent burn trying to do a tricky repair. A pistol grip would have made it easier (on the other hand, if I had not turned the heat right up I would have been fine).