The final result of this tutorial:
I've rotated my lightsaber around (R) with both the handle and the two blades selected in order to fit in the camera viewport better; I also moved the lamp, and adjusted the halo size. This can be done here:
Now when you render, you should get a result like this:
Now, for our purposes we want something better than just a dull, grey background, so let's change that. Select 'Blend Sky', then change the Horizon color to a very dark purple, and the Zenith color to a very dark blue. You should now get something like this:
Notice how I also changed the halo settings more; if you want your halo size smaller, but if you make it smaller you can see individual dots, simply go into Edit Mode and subdivide it again. Now our background still looks a little drab, so let's add something else to it. Go to the world buttons, and enable 'Stars', then click the little arrow that drops the menu down. Set the size to .04, the Colors to .25, and the Separation to 2. Also, you may have noticed that my camera dimensions are different than yours. In case you want the same, these are: 1280 by 720, rendered at 65%.
Now we should get something like this if we render:
That's good enough for now, so let's move on to the compositing. All we'll be doing is adding some Chromatic Aberration. Change the screen from 'Default' to 'Compositing'.
Select 'Use Nodes'. Two nodes will appear on the screen; move the Render Layer node to the upper left corner, and the Composite node to the lower right. You should now have a setup like this:
Now add a Lens Distortion node (Shift A - Distort - Lens Distortion), and connect the nodes as shown below (Click and drag).
Set the 'Dispersion' at 0.015, and render. Congrats! You have finished the 3rd part of this blender tutorial! If you have any questions, comments, or problems, post them in the comments below. Thanks for reading!