If you’d want to do eevee it’d be a different approach I think, since there are some limitations with shaders nodes.
Maybe you can try putting lights or a small piece of emissive geo behind the object and put a shrinkwrap constraint onto them, pointing to the sword. That’d sortof keep them stuck to the back of the object. If your using area light you’d also need to put a track to constraint pointing away from the camera. You’d have limited success whit this though, but worth a try maybe.
As Mario said, doing it in post is another way to go.
Or make the sword emit particles, make a strong forcefield constrained to the camera, blowing them away from the cameras view, short life span, emissive material… Didn’t try this one but with a small particle size it might just work.