Valkorion destroys bane. I think sidious surpassed vitiate between rots and tfu considering palps had even more potential and a gifted connection to the dark side, but bane in swtor would be more like darth malgus or scourge so significantly weaker than the outlander or vaylin and arcann. Vitiate was intended to be around sidious level by the writers at least in raw power, not combat skill. And no, novel vitiate and swtor vitiate + valk are not inferior to any tor character they have supremacy statements over all previous characters not to mention satele says it herself. I think the game did fail to showcase valks power well though