As discussed here : Link here is a feature request for glow. It's when I look at Maria Grønlund's work that I realize how important Glow can be.
It could for example be an "Add Glow to 3D object" node. We could input an object and specify the glow color and its width. However, I don't know if it would be better to have an unique color for the whole object or to be able to use the colors of the object itself to glow, allowing to reflect the different colors different parts of the object could have. That's perhaps more something like Blur with more light.
PS: This would perhaps be great for Layers too.
Here below is an example of Maria Grønlund's work on Behance. Her entire Work can be seen here : Maria Grønlund
Image Credit : Maria Grønlund