farming with the upgrade of sundering

ok guys and girls I have one question dealing with sundering, lets say you have a 10/10 sundering on your sword or on your axe (if there is one..I havnt seen one but i bet there is) then you gather like 15-20 enemies around you and you use hundred blades or cyclone axe. does the sundering 10/10 work for each shot, so you would have a 10% chance each strike or is it one chance to hit every single enemy with the 10% penetration? just a question.