Energy sword would be an honorable mention at best for me. Enjoyed Halo for a while but when I think of awesome "swords", it doesn't come to mind.
More of a Soulcalibur guy, personally. Though I get the reasoning of why you went with Soul Edge for this article. I'd also probably take Red Queen over Rebellion in DMC 4. Motorcycle blade FTW.
Another thing I'd probably mention are the moonlight greatswords. You see them in most of FROM's games. Usually look pretty neat and pack a punch.
I've seen screens of Guan Ping's Mystic Splitter in Warriors Orochi 3 Ultimate and that one is badass as well. This was a neat idea for a top 5.