Star Wars: What Happened To Count Dooku BEFORE He Was A Sith

Eventually Dooku achieved the rank of Jedi Master and became a member of the Jedi Council. He took on Padawan Rael Averross as his apprentice and would train him until he became a Jedi Knight.

Once he became a Master, Dooku abandoned his original saber, and created a curved-hilted lightsaber like that of Darth Sakia, but with a blue blade. Dooku became a lightsaber instructor for Thranta Clan and demonstrated lightsaber skills with Yoda.