I'll keep this mostly in spoiler mod.
Okay, in Viorian's entry and history it talks about how she was possessed by Chellan 5 years before when Karzoug woke, and it drug her to Xin-Shalast. There she's spent 5 years training under Chellan's command, and at this point is "little more than a mindless shell controlled by the sword of greed".
Now, this seems very odd to me as:
A) Chellan isn't an intelligent weapon
B) It talks about her pledging herself to Karzoug's service, when if mind controlled it seems very strange.
Since my party is all too likely to try to redeem her rather than kill her outright, my question is this: How should I go about allowing them to heal her of the damage that's been done? Break Enchantment on a new enchantment she's under, and which would be revealed in Arcane Sight? Removal of the weapon followed by a Greater Restoration? I'm just curious what other people think, as I'm still debating how to go about things.
Spoilered for safety's sake ;)
Maybe Chellan is supposed to be sentient (the text just got cut), and somehow transfers its essence from the blade to the body of its wielder, subverting that being's own soul in the process. If the wielder dies, the essence returns to the blade again, ready to ensnare the next unlucky soul.
On the other hand, there is no mention of any sentience in Asheia, the Sword of Lust in Seven Swords of Sin, so it is a bit of a puzzler. Unless the sentience is conditional upon the awakened presence of the sword's Runelord in Golarion, then the idea could still work...
Anywhoo - I too am probably going to have the PCs try to redeem her, if they can figure out she's possessed (which should be pretty easy to tell considering how the giants are behaving around her).
I think your spell suggestions are spot on - separating the weapon from Viorian and then hitting her with Break Enchantment would sever the connection with Chellan. Then she would need a Greater Restorationto get her own faculties back. Maybe even a Limited Wish - not sure on that though.
I hope that helps a little :)
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