Lightsabers are the weapon of a Jedi, Light, Dark, or otherwise. By using special crystals and a complex hilt, A beam of cutting light (much like a laser) is generated in the shape of a sword. How does a lightsaber work?
Lightsabers can cut through almost anything, excluding other lightsabers, Cortosis (which shuts down a lightsaber), Phrik Alloy (which resists lightsabers), and Mandalorian Iron (which resists lightsabers.
In the Dark Brotherhood, A member is not permitted to have a Lightsaber displayyed on their Dossier until they have reached the rank of Dark Jedi Knight. When they are knighted, they are allowed to fabricate their lightsaber using a special, web-based tool which allows them to pick through many different hilts, colors, and blade colors.
Those that can not yet have a lightsaber on their dossier are permitted the use of Training Lightsabers, provided they meet certain criteria. These lightsabers are not as powerful as the regular ones, but are a valuable training tool.
Fighting with lightsabers is a test of skill. Many millennia have passed in generation of very specialized and effective forms of Lightsaber Combat, including methods on how to fight with Dual Lightsabers and the Saber-Staff.
Even more rare than those who have the training to use two lightsabers at once, or use the double-sided lightsaber, are those few who have been awarded the Golden Lightsaber Award.