alpha over node is adding to the foreground artifact that is not in the background i'm using blender 2.8 beta and i'm trying to conduct a test in which i make a lightsaber without volume for the haze so that the rendition isn't to long, so i used 2 view layers (used to be called render layers) one of the blade and one of everything else so that in the compositor i can change the blade color, and then blur it, and then use a alpha over node to use it for the background of the other view layer. yet it adds a green to the edge of the handle.]2 

i'm trying to get rid of the green artifact around the handle of the lightsaber. it is more clear with colors other then white around it but alpha is replaced with white on this site. on the compositer screenshot i gave shows more clearly the problem
I'm not really sure what you're trying to do, sorry.  This might help, might not: https://uvassociates.in/sites/default/files/resize/remote/c0631e46351ca76e7380488b072beb7f-400x312.png

It makes a mesh invisible and just renders the light from it.  It's an older version of Blender, so may not work.  GL