There was an article written up awhile back on how to do this, I believe by Chienworks. Do a search on light saber and you should come up with some ideas.
Hey, i can't find crap on how to do special effects in vegas. How about everyone else around here, how can i make like explosions, light sabers, and other special effects using one program which is VEGAS. Thanks
You can do some special effects with the add-in program WAX from www.debugmode.com. This includes some 3-D stuff, exploding particle effects and the like. It's limited but it's pretty cool and it's FREE. Also, there's a video morphing program and a frame serving program at the same place.
Other than that, I think you have to buy programs that let you draw on video. You might be able to do some stuff with generated media, masks, and bezier curves, but it's probably not too easy.
Vegas is great, but don't expect to become George Lucas overnight! :)
Actually, Wax has a draw-on (rotoscoping) function that works pretty well. And it's free, so even if it isn't EXACTLY what you are looking for, it is much better than NOT FINDING CRAP, and it is easy to find. If you didn't see above:
It's got an explosion, a moving target, a laser gunsight, animated background, overlays ... ok, i'm hyping it up a lot more than it deserves. But, it is completely 100% Vegas!
If you want special effects then you're going to have to use other software. Vegas is an editor, not a special effects program. Yeah, there's a lot you can coax it into doing, but there's a whole lot more it doesn't do.
If you plan on doing a lot of stuff like this you should invest in a copy of ParticleIllusion, it has all the explosions light sabers and everything else you could ever want. You might even be able to still order the back issue of Digit magazine that came with the very good free LE version of it.
Or check out AlamDV 2 Lots of effects you can do in there and then import back in to Vegas. And AlamDV3 should be out any day,umm month,errr, year now too.
Open up the video clip, put the effects on the timeline wherever you want them, couldn't be more simple than that. Or just make the effects over a blue or green screen and then chroma key them out in Vegas.