Building on my previous post, I'd also emphasize that this ability is very subtle in its manifestation. He's a silver-tongued devil. His eyes don't glow, he doesn't chant magical phrases. He just says "Protect me from this brute, won't you, my dear?" to the barmaid... and suddenly she's ready to fling herself on your sword to save him. When he drops the control, she doesn't even know what happened - a moment ago, it all made perfect sense. Among other things, this also means that to observers, if you attack him and kill her, it looks like you're entirely at fault. Yes, it's his Price of Loyalty power at work, but that's the mechanics of it; metagame, it's that the people he dominates are willing to die to protect him.
Again, when it comes to "how come he can do this and I can't?" - it's because he's a ruthless mastermind who may have spent seven decades and made disturbing pacts to gain this power. You COULD learn this power - if you lived his life, dined on illithid brains for a year (made possible by his ridiculous wealth), made the blood sacrifices he's made, murdered your own brother, and were an utter sociopath (as that's the mindset you need for this to work). He's a dwarf. You're a dwarf. Unless it's a bloodline thing - which it could be, as dragonmarks show - you COULD learn it. But you can't learn it the casual way you learn your next utility power, because that's not the sort of thing it is. He's a character with his own deep history, and if it were me I'd make this ability something he's made a lot of sacrifices to acquire - something explaining why he's such a powerful and influential individual.
As a side note: The Aurum isn't a monolithic organization. As a rule, each powerful member of the Aurum is unique. One might be a crime lord, another a dragonmarked baron, another a Mror banker. Each one has SOMETHING that gives them the power to influence others - something that has let them earn their place in the Concord. But this Concordian is one example of that. This doesn't mean that EVERY Concordian has cool mind-control powers; it's this guys particular angle. If it was me, I'd use it to make this guy a truly memorable and long-term villain. My point is simply that it's not supposed to be a casual "Everyone in this secret society mind controls, why can't I" thing; it's "This particular mastermind is a mind controller."