Is your human character immune to Sion's charisma?
Raine is only half human, and in many respects her elven blood is what dominates, so I'd go with little if any effect.
China is fully human, but... pulls a very similar trick in a very different way, and has a general disdain for Emotions. She might notice the pull, perhaps? Or just ignore it entirely.

Any blackmail information that Sion could find via digging
Raine is pretty open and not disreputable. She keeps information close to her chest, but it's nothing blackmail-worthy, just stuff she prefers she not be general knowledge. Should be pretty evident that threats to the people she cares about are the best way to leverage her, though. There's one thing that only three people currently know which I would really prefer not see the light of day, though, and it's never been on the network, so I don't see how Sion could hear about it anyway.
China is for the most part utterly shameless, an information broker, and the one thing she's ever been blackmailed with in canon is no longer usable leverage. I can't honestly think there's anything that could be used on her, though her lack of fondness for Anton Shudder might be a thing that can be picked up on?
General Opt-Out for Asruld Shenanigans:
Hearing Asruld?: Sure, if it comes up.
Sword: Sure also, if it winds up being a thing. Though Raine is magically/spiritually inclined to light, if that would affect anything.