'Trials of the Darksaber' and the previous installment, 'Warhead' were originally conceived as one episode. During a story pitch in July 2015, the events depicted in Warhead were to be the B-story while those from 'Trials of the Darksaber' would have been the main focus as the the A-story.
The Clan Vizla member that broke into the Jedi Temple and looted the Darksaber may have been Shae Vizla, the Mandalorian that helped Sith Lord Darth Malgus attack the Jedi Temple and disable the planetary defense net during the Sacking of Coruscant in 3653 BBY, which is described in the prelude to Star Wars: The Old Republic (2011). Shae Vizla was one of the most famous members of Clan Vizla, she assisted the Sith Empire in a number of battles against the Republic and Jedi Order during the Great Galactic War of 3681-3653 BBY. When the forces of Zakuul invaded the galaxy in 3637 BBY and defeated both the Republic and the Empire, Mandalore the Vindicated (the current leader of the Mandalorians) was killed and Shae was elected to become the new leader of the Mandalorians and was known by the name Mandalore the Avenger. She also became a player companion in the expansion Star Wars: The Old Republic - Knights of the Eternal Throne (2016).
The working title for 'Trials of the Darksaber' was 'The Blade Trials'.