Darth Vader lays out a cruel test on Dorme, who was pretending to be the handmaiden Sabe, and confirms that she’s not who she said she was. By making her shoot two stormtroopers, Dorme chose not to finish the job and kill them, revealing her merciful nature. Vader claims Sabe would have killed them with no problem.
From – Star Wars: Darth Vader Vol. 1 #29