I understand why you want to replace Social Standing (not really an attribute) with something that can replace it in any setting, be it a Imperial / quasi-feudal system like the 3I, or free space, pure democracy, representative republic, corporate run space, or what ever. Not every culture cares about "who is commoner and who is a Baron". Will power IMO represents the persons strength of spirit, inner strength, the ability to resist cake and ice cream when he's on a diet, or the will not to take a bribe, or cheat on a spouse. It can also be used to fight off the effects of some psionic attacks, or non-psi manipulation like interrogation etc..., or even forcing yourself to push the limit of your endurance to cross the finish line when you should have dropped from exhaustion 1 kilometer from the end of the race. But for social settings, upward mobility, the ability to say the right thing at the right time, and to whom to say it and how to behave. It would help with skills of persuasion, fast talking, etiquette, carousing, etc...
So for a generic "attribute" that can take the place of social standing, I think Charisma fits better than will power. Although as the examples above show, will power can be just as important.
As of now both these attributes are simply rolled into IQ. But I'm met VERY smart people who completely freeze in general social settings, parties etc... and who have terrible will power vs keeping to "new years resolutions" etc...
Just some thoughts.
