Hey, you know that one scene in Return of the Jedi Where Darth brings Luke to The Emperor and he says “Ah, yes. A Jedi’s weapon, much like your father’s” Would that mean only the Jedi (Pre Prequels/EU) used them officially labeled as their own weapon?
Meaning that Vader would be the only Sith in out of all to use one as his own.
Note: The term Sith was used in one of the original scripts for SW77
JEDIT:
That makes me theorize that the previous Sith before Vader only used their force abilities/powers and other.
I think The Emperor was just mocking Luke’s progress as a Jedi. I also think that at the time, the intention was that “the Sith” were Jedi who had pledged themselves to The Emperor when the Jedi Purge began. Vader was low-ranked amongst them, hence his “I was but the learner” line in ANH.