Lots of ways to do this. Here's the easiest that comes to mind: 1. create a new layer 2. set foreground color to the glow color you want 3. using a paintbrush roughly the same width of your saber(maybe a littel wider) paint a line that covers your glowing object. (use whatever method you prefer, just mask out the bit you want to glow) 4. Apply a gaussian blur. I would suggest @10px for this size of a pic. 5. Set the layer blending to Screen. 6. Duplicate the layer a few times until you feel the glow is bright enough