I am curious about their locations as well. I found one in Assault on the Control Room, which I understand is supposed to be hiding two. All the map files, when opened in Assembly, reveal the Energy Sword is in all levels. Ruby I think said so in his hour long show case.

Some need to triggered or have the game played a certain way in order to be found or appear at all. A complete list on how to get them and where their located would be great.