The recommendation made by robert piepenbrink is valid, and standard practice:
1) Have an open pot of boiling water at hand.
2) Have a bowl of ice water at hand.
3) Immerse the bent plastic into the boiling water, covering the part you want straightened, immersing it for 20-30 seconds, to soften the plastic (water boils at 212 F/100 C, while most thermal plastics melt at 300+ F/150+ C, so the water is hot enough to soften most plastics, but not hot enough to melt them). Avoid burning yourself!
4) Straighten and hold the plastic in position, then immerse it into the ice water, immediately, while still hot. Leave it immersed in the ice water for another 20-30 seconds, to allow it to rapidly, fully cool, resetting the plastic's memory, fixing it in the new position.
It can be challenging to achieve a good result using this technique. Repeated attempts can be made, always being careful.
If that fails, you can order yourself a set of 28mm Wire Spears: cut off and glue the plastic pole arm heads to these metal shafts; insert and glue the shaft into the hands of your figures. You will need a pin vise to drill out the miniature's hands to hold the metal shafts.
Try robert's suggestion first. Put my metal spear suggestion in your back pocket for future reference. Cheers!
