Body Cracks:
I just use a boxcutter scribing in cracks on an angle, again - practice on old CD cases.
Cuts & more Severe Damage:
Dremel and cutting disc will get the job done. This more than anything else shown here is what will take the most practise to perfect so practice on what you can - KO's other toys etc.
Blown Off Hand:
Remove fist, cut the end of the arm off at the wrist.
Cut in lines of different depths and widen the cuts where the wrist was.
Try to arrange the blown off tips at different heights and sharpen them up a little with the dremel & disc.
The damage is done !