Not a huge deal, but lightsaber forms sound cool.
http://xbox.ign.com/articles/563/563609p2.html
http://xbox.ign.com/articles/563/563609p2.html
There are even rumors of an exceedingly rare type of crystal that bonds with its owner, becoming more powerful as they do. The bond is so great that the crystal's capabilities and color even vary with its master's alignment towards the light or dark side of the Force.
Lightsabers can also be upgraded with new power cells, emitters, and lenses. These upgrades can be found throughout the game, but, using skills, can also even be created! There are more than 60 possible lightsaber upgrades, yielding over ten million possible combinations.
Kevin Saunders: In KOTOR II, you can learn up to six of the seven Jedi Lightsaber Forms. These are fighting techniques whose effectiveness depends upon the tactical situation. Each form shines in certain conditions, but also has weaknesses. Learning the characteristics of the Lightsaber Forms, and switching between them as the combat situation changes, can allow a Jedi to prevail in what would otherwise be a fatal encounter.