Vivec was his mentor, Sermons aside. Nerevar had a deep understanding with him, and you cannot deny that. Truth to benevolence is that Vivec doesn't really 'lie' in the sermons (unless hes fire mask is on. Then, WATCH OUT!), he just likes to absorb himself into his own truths. Or, the truths of others. Or, the half-truths of others, to be on the spot. It's not hard to assume that he knows what he's doing, considering he even finds himself so condescending some times. I bet Cyrus thought he got the best of him, too. But that's besides the point.
And I never specified which did kill him. But, he's still dead, so left hand or right hand, doesn't matter. He's still gone. And he may or may not admit it (depending on how you take his words), but he also probably did it single-handedly. I'm sure Almalexia and Sotha Sil just watched the door and whistled a healthy tune while it went on.
*sigh*
Vehk was his adviser ad friend, almost every text about thiss accept the sermons says this.
Vehk the mortal killed nerevar vehk the god did not, there are two diffrent realitys one that vehk himself created(the sermons) and what really(I can't think of any thing better to say)happened, both are true which is why vehk is half chimer and half dunmer.
Lord hyamantar could you please explain furthur. I'm too lazy to look for links.