Rebaslight, an open-source special effects editor, is easy to use. It allows you to add lightsabers to your videos, lightning effects, and different types of muzzle flashes, among other things.
Rebaslight is free to use (no cost) as long as the "Made with Rebaslight” watermark appears on the output image/video. This watermark can be removed forever if you pay $25 one-time.
Version 3.6.2: