Is something to obscure our aura a possibility? If not to outright hide it then to dampen the ability of others to detect it from long range?
Sort of?
The good and bad thing about prodigies is that they are defined more by utility bands than by a set of specific effects they're limited to. There's a 3 dot sample prodigy that lets you travel through time, but only forwards to midnight, and a 4 dot that gives you a sword that wields itself, but is mostly mid grade mortal in skill.
So technically prodigies should be able to generate such an effect, the question just becomes what it costs to do it.
1-2 dots can be done with essence alone. 3 dots need to be done in a dragon nest and require a middle tier reagent; blood of a vampire, rare magic mushrooms, it doesn't have to be combat based just magical and somewhat limited in supply. 4+ need captured monster essence.
Hiding our aura is a big job, but 5 dots is the level of stuff that swings a campaign in a particular direction so my estimation would be 4 dots. We don't have a reagent for that, but prodigies can be adjusted by adding complications.
Making it cost essence/willpower to use, have a cool down time that stops us from using it all the time, or something entertaining like periodically needing a discharge of undirected infernal essence that produces an obvious spike when we turn it off, could all fit the bill.
It comes down to if DP agrees with the argument for a particular item more than a matter of specific black and white rules.
I really doubt that.
I think it's unlikely that the shadow here has the power to apply even social Charms.
She didn't against Harry so far, just high stats (humanly high stats, not what you'd expect from an Elder Exalted).
Not everyone accomplishes the same effort he same way, and the effort involved is different depending on how you have to do it.
We have to spend essence to get inhuman sword skills, but building an arcana that rolls 14 melee dice passively isn't that difficult. Flight is an ability that Dresden considered impossible to do with mortal magic (though it turns out high level people can cheat their way into it to an extent), but we can technically roll to activate it through BRR for free. Agg damage is slightly easier to acquire, but for most it's not nearly as easy as we have it.
Lash isn't human, she's a spirit imprint of Lasciel packed with everything her originator could give her to influence people. She isn't drawing on supernatural power to be persuasive, she's drawing on inhuman intelligence and experience.
Exalts are the ones who need all that power to break into the areas spirits like this rest at, she shouldn't need gobs of power to play at this level.
Harry gets by with the fact that you can burn willpower to ignore a social attack and that he can muzzle her most of the time, so she can't tap his willpower and then start brain bending him. If he couldn't lock her up she'd have turned him by now.