(havn't read all the other posts so I may cover the same ground, if I do, sorry)
The big issue is that we don't fully know how a cyber limb is made, how it's internal components are assembled, or where the load bearing stress factors are.
For example: is the outer shell of the cyberarm (reguardless of 'skin') the load stress factor? Or is there an internal component similar to natural bones that bares the stress? (this is important!)
If it is the outside shells that is the load stress, then the internal parts of the cyber limb is all wires, servos, motors, pumps and hydrolics. When you go to punch someone with this cyberarm, part of the kenetic force of the punch is directed into a small area of the shell (and possibly denting it... Like a ball thrown at the side panel of your car) the rest is transferred to the internal workings of the arm and absorbed. (look at your hand, make a fist... Where your knuckles are, would be small moving servos... And they COULD be broken by the impact;) another issue is that it is possible that the arm won't allow you to hit 'as hard' as it is capable to stop damage to the arm.
If there is an internal stress load for the arm, then chances are the outer shell (regardless of 'skin') is there for safety and cosmetic purposes and thus made up of kinetic absorbing materials to prevent denting and other unsightly damage through everyday contact. IF this is the case, then that outer shell is working directly against your punch by absorbing some of the impact into itself by design!
Lastly, make a fist again and look at it. A good thrown punch will hit with the knuckles of the index and middle finger first as these are the only 2 fingers/knuckles with ridged structure (your last 2 fingers/bottom part of hand have many small bones and cartaledge... Good shock absorption to a point) next look at the skin over your first two knuckles... It's not very thick is it? (unless you are obese). This means there is very little padding in the way of the bones so there is little abdorbtion by your skin from your punch...
Now add in your bone density or lacing, making those bones supper dense (and limiting the bones natural shock abdorbtion) or armoring them. Both will allow you to exert way more force than an unaugmented (and possibly a cyber limb) would be able to do and not suffer injury.
Sadly however, until we understand how the limb is made, we can't really answer your question, and have to trust that the Devs took the cyber limb construction into account when they determined the damage code.