(2) That doesn't address the issue at all. Perhaps the snake bladders improved his inner strength by 50 points, enabling him to lift the sword, and the sword training further gave him 200 points. The snake bladders were important, but the training could still have been much more important.
(3) There is clearly some technique to it besides simple, straight forward strikes even if that is the underlying theory. Every martial artist understood that principle, with Dragon Palms having the exact same principle, yet it is differentiated in some way. I just assume it is some wuxia mechanic where the idea is supposed to be extremely profound, but there is no way to convey it to the reader except in a more mundane and understandable way.
I don't consider YG having "lost out" in that exchange since both weapons were knocked away. I don't see how you can judge that in any way but a draw. No Great could take GWM head on as in take the full force of his blows.
(1) ZBT was able to only defend, because he dared not received the blow head on. YG is able to take the blow head on and attack/defend. I would say he has the advantage.
(2) Yideng and GWM dodged each other's blows iirc. He would not be able to take the force head on.
(3) The only instance of HYS against GWM is when he flicked a pebble at his wheel from far away, and GWM was amazed at how much strength there was. I don't know if that's the same scene you are describing, but that is hardly head on and GWM certainly did not dodge it.
Either way, I don't see YG as being weaker than the Greats in any way, with or without HIS, and with or without Sad Palms. Give him either and he would likely beat them, and give him HIS and he would definitely beat them.