So long story short, player A is a techpriest, Str 32 T 34, using a Servo arm, Str 75 Unnatural (7). Player B is an Ogryn is using his bare hands, Str 53 Unnatural (2), T 55 and Bulging Biceps. The Techpriest is trying to grapple the Ogryn for whatever reason that his circuits said this was a good idea. Now I know that the Servo arm is strong enough to pick up the ogryn and toss him like a frisbee, however Player A isn't strong enough to support the weight above his head. Player B wanted to know if he can just lean back and spin til the Servo arm rips out of the spine socket, or just kick him in the chest, realizing that the servo arm would still be trying to grip the hell out of him, but the techpriest would be bleeding about 10 feet away sans arm. I can sympathize with the latter scenario, as a professional football player versus a 9 year old that has a Dr. Octopus super arm, but is there anything in the rulebook to help adjudicate this?
Grappling Vs Cybernetics
My understanding of the design of the servo arm is that it's meant to lift tanks, and is able to deploy some support struts in order to make this actually work (at which point it's a grimdark car jack).
The combat stats for this weapon are absolutely ridiculous. This god awful thing can outclass entire character builds and almost entirely outmodes weapons short of a power fist.
If he uses in a grapple, the Ogryn will need to beat the arm's strength to get much done.
Mechanically the Ogryn is testing against 53, the TP is testing against 75. A maneuvre like those described is equivalently the narrative effect of winning the grapple check. You have to remember that the Servo Arm is anchored to more than just the spine - it's an integral part of the Techpriest's cybermantle and skeletal structure at this point. If anything, this is harder than ripping the Ogryn's arms out of his socket would be.
Yeah, if you look at DH1, "Tech-Priests" didn't even get their servo-arms; they only got various, flimsy mechadendrites, and Ascension, I think, gave them the Power Fist on a stick. In that way, receiving your Servo-arm was sort of like a milestone, and the procedure also included internal reinforcements; as was said, a standard enginseer can lift a Leman Russ off the ground, at one side, to repair kinked treads, ad what not, possibly going underneath, to patch the hole a buried tank trap charge might have made in her. At that point, the Ogryn isn't ripping that thing out easily.
Just be glad that the servo-arm doesn't count as a Power fist; I seem to remember at one time, it did, and it could be a cool upgrade for a high-ranking TP. The claw can tear armor plates, though, like a power fist would.