The Thaissen crystal saber was a lightsaber design crafted by the Night Jedi of Endor. It used a Thaissen crystal to provide its colour, and hence, its colour reflected the Force alignment of those nearby.
When in use by the Night Jedi, the saber would ignite taking a purple colour, and change to reflect the force alignment of the opponent.
Behind the ScenesEdit
The crystal was sometimes misspelt as 'Thalassan', or 'Thallasian', leading to confusion with the planet of a similar name.