The big moment is coming . . .

Heres my two cents... Dark Jedi and Sith are two very different things... Palpatine was indeed a Sith lord. Tarkin more than likely knew this. However, I believe that Vader was not a Sith, but a Dark Jedi. And, when you really get down to it, to the average person, a Sith is just a glorified Jedi with a religion backing him up... The differences are on a technical level. So, even if Vader is considered a Sith, he began his life as a Dark Jedi.

 

Ill agree with you up till Dark Lord. After this point vader becomes more and more ingrained in the teachings of the sith rather than sheer jedi gone angry.

But during the events of RoTS, yes, vader was only a dark jedi despite his title.

 

Neither really, only that its possible to take the quote from ANH both ways without anything else to put it into any real context, as calling Vader the last Jedi isn't necessarily ruling out knowing that Palpatine was a Sith (as, after all, Palpatine wasn't a Jedi, only Vader).

 

Oh, you meant after Palpatine declares himself Emperor. My mistake.