What is the L-key in Jedi Knight II for (I play PC)? The controls section says it's to change the attack stance but it doesn't do anything in the game...

lol- you just need to progress farther in the game. There are three lightsaber attack styles: Beginner (blue bar in your Force counter), Fast (yellow bar in your Force counter), and Hard (red bar in your Force counter). Each attack has its ups and downs, though fast and hard are obviously the two best styles of combat. As you progress in the game you learn new Force skills- and new styles of lightsaber combat.

 

I think when you get to the end of the Bespin missions you'll be able to use fast style. It's been a while since I played the whole game through. I just like playing the penultimate level with my saberrealisticcombat cheat. Have you used that cheat yet? You won't regret it.

Thanks for the answer! I have yet to try the cheat... but don't worry: I will... You posted it in BoPC, right?

Yup. It's particularly fun to use it on the penultimate level, when you get there. Particularly if you beat the game on Hard beforehand. It adds a whole new level of difficulty, even whilst on easy, if you play it with the code and no god mode.