Have you tried messing wiht the add/ and hard settings of the halo material? add is brightness, which can make a big white outline, and hard is how much the halo fades as it extends. You may also want to try turning down your halo size
just some thoughts, sorry if Im echoing anybody else
ARG!!!
After messing with the settings more, I’m STILL getting fat glows!!!
OH well. Looks like I will have to use your blade LOTR Junkie 
Those lines look like they were subdivided TOO much. Give it one more shot, if it doesn’t work then oh well, at least you tried.
PS Keep me updated on your film progress, I’d like to see it!
Hmm…the blades from the file I saved are subdivided to 1027 verts, and in that file, which I didn’t save, I subdivided them to about 8000 verts 
What vert count do you suggest, if that’s possible?
Whatever makes the glow look good! I suggest subdividing once, rendering, then repeating if the glow isn’t right. If you go one too far, ctrl+Z.
[Edit] In my file, both lines are 257 verts. Scaling matters in this issue though, that’s why I suggested the above method. Remember, halo intensity depends on how close the vertices are to each other, not how many there are.
Alright!! I think I got it!!!
Check it out:
My blade:
Compared to Jason’s blade:
I think you were right about subdividing too much 
EDIT: Actually, I was messing with the settings, and I got this:
However, maybe they’re the same, and the other one is just a different angle?
Apparently, 'cause it is at a different angle when I looked in your file. What does that do to it, and how did you know how to do it?