All I can say is you must like pain if you’re willing to do it that way.
You can load sequences into the sequence editor or the nodes compositor, nodes being easiest and most versatile. For nodes: Spacebar>Add>Input>Image. Click load new on the bottom of your image node and select the first frame of the sequence. In the top left field of the image node set the number of frames that the sequence contains. Be sure to turn off all options on the “Layer” field and “Passes” field of the render layers tab if you have no geometry to composite. Do the same for both sequences and combine them with an alpha over node (Add>Color>Alpha Over). You won’t need more than the single default renderlayer because you won’t actually be rendering a renderlayer anyway.
For sequence editor Add>Image and just right click and drag over all frames in the sequence then press enter. Do the same for both sequences then combine them with an alpha over strip. This is much more limiting than the nodes where you can add effects such as vector blur, blah, blah, blah.
Be sure that you set your time line to match the start number for the first frame in the animation if you use nodes, eg if start # of sequence is frame 158 with 210 frames set your timeline to start at frame 158 and end at frame 368.
I personally had little trouble setting up a light saber. Here’s a screenie and a link to the .blend
Your end product would look a lot better if you had a better hilt for your lightsaber. Obiwan, Luke and Darth Vader’s original lightsabers were constructed mostly from plumbing parts available at just about every local hardware store.