Initially, I thought the same as @Bejardin1250, but I'm not sure anymore.
Honestly, based on what I remember of Vargo's emotional days, he was an empathetic and compassionate man, in a soft way iykwim. Though Odium has been associated with passion in-text, I don't really see any connection between his increased emotional capacity and the emotional fury of the Shard. I think that this definitely shows in the quote that @Honorless added. He's very internally conflicted.
In the coppermind, we have this quote:
So maybe Cultivation was attempting to forge a Connection between Taravangian and Odium? If so, I'm kinda skeptical of whether or not it worked. Odium and emotion:
I don't think that lines up well with Taravangian and his experiences.
Another take is the Cultivation-is-evil route, and honestly I think that makes the most sense to me as of now? Idk where but there's the pretty infamous quote about odium being most dangerous in the hands of someone smart and scheming, like Taravangian... Cultivation has to have known that. Man, I need to reread that whole section.
Anyways, back to the main question, (if a shard has power over an individual, and that individual ascends, does that influence remain?) if, after ascension, Taravangian is still affected by Cultivation, would that give Cultivation power over Odium? I can see that as a motive for what she did.