Who was speaking to Ahsoka when she spoke of revenge?

Question

In the finale of Star Wars Rebels season 2, Ahsoka confronted Darth Vader and part of the conversation went as follows:

Darth Vader: Anakin Skywalker was weak. I destroyed him.
Ahsoka: ...Then I will avenge his death.
Darth Vader: Revenge is not the Jedi way.
Ahsoka: I'm no Jedi.

Darth Vader's response to Ahsoka's desire for revenge feels somewhat odd to me. Why would he care to remind Ahsoka of that point? I guess it may not exactly be out of place for Darth Vader to say that, though I cannot exactly fathom why he would. Or is there a remote chance that, already at that point, the Anakin within him has already surfaced, trying to dissuade Ahsoka from this path?

Who is the one speaking that line: Anakin Skywalker or Darth Vader? And why?

Answer 1

Considering his previous statement was literally "Anakin Skywalker was weak. I destroyed him." and the tone which he took in saying so, I think we can safely say that the Anakin persona had not surfaced.

More likely, we rarely find those with lightsabers are force abilities to not be associated with Jedi or Sith (although admittedly, such is more common at the end of Clone Wars and throughout Rebels). Being that Ahsoka is actively working with the Jedi protagonists, and given her past as a Jedi, it may not have been all that odd for Vader to assume she had gone back to following the Jedi way (after all, in a sense she did in principle behave and function as a Jedi would, even though in name she makes it clear that she does not identify herself as such).

Because of this, and given his past knowledge her character, it makes sense for him to be surprised that she would go so far as to seek revenge, something very "anti-Jedi" of her to do. Ultimately, it also serves to show that just as he changed since their last encounter, so had she.

EDIT:

It's also possible that it may have been a lead-in to turning her to the dark side. Pointing out ways that she had already started on the path, much like he did with Luke, could have been the start of his attempt to convert her. But after her response and readying for battle, it became clear that the time to continue such banter had passed.