don't know, did you change anything at all? only way i can even get a reproduction of what you discribed is by eliminating the vertex incrementation routine in the script
or by editing the model and deleting all the un-attached vertexs ( which you need )
Everyhting appears, just the lightsaber doesnt extend, almost as if the particles lifespan dies before it reaches its intended vector. Or its intended vector is messed up. (Like its not incrememting upwards) I tried upping the lifespan to no effect.