That picture and the whole description of Nerevar's death still bothers me.
The picture shows the murder as a violent attack. Perhaps it is symbolic rather than literal.
The account from Alandro Sul says that the Tribunal poisoned Nerevar. This murder happened prior to anyone confronting Dagoth Ur. In this account, the Tribunal murders Nerevar and then they go fight Dagoth.
But in game, Dagoth clearly states that Nerevar fought him. He is hurt because he feels like you (or your past incarnation) betrayed him. When I first heard this, I thought it meant that Nerevar couldn't have been murdered (since the murder supposedly happened prior to Nerevar re-entering Red Mountain.)
But then the 36 Lessons' secret message admits to the murder, as does Vivec in the Trial.
So we know the Tribunal killed Nerevar, but did they do it with the sword (as in the picture) or with poison (as in the account)?
We also know that Nerevar did fight Dagoth Ur. But this would suggest that he was killed after re-entering Red Mountain.
Why would Sul be right about the murder but wrong about the method and timing? Wasn't he supposedly a witness?