Courtesy of http://www.he-man.us
This fix is intended for accessories made out of the same type material as vintage MOTU accessories. It may however work on many more!
Bent Weapon in need to straightening
Boil some water, and lower the accessory in with a spaghetti spoon. Do not let it touch the bottom of the pot, or it may melt.
When it straightens out on its own after 1 or 2 minutes, pull it out and cool. (toyfixer.com note: I find if you cool it fast it retains shape better)
If it doesnt straighten itself, a little manipulation may be needed.