of course they need to be textured with a glowing something, fading to black on the edges. Probably you want to use entityorder to make them apear in front of everything.
Use the additional Blendmode for the Sprites. Now if you move the sword, this string of sprites will be attached to the blade, and face always to the camera.
Use the additional Blendmode for the Sprites. Now if you move the sword, this string of sprites will be attached to the blade, and face always to the camera.