The whole "varying intensities" thing would be very complicated to implement, and could also result in a huge performance hit (especially if alpha blending is used).
I'm going to narrow the scope down a bit here. I am open to the following changes, specifically:
1. Making the whole beam wider or narrower. Not "different thickness at different points" (but it could be different in different frames of the animation, as long as it's the same for the entire beam in any single frame). However, the beam will remain just a straight line in one or more colors.
2. Altering the colors of the beams in the direction of the laser. To be clear about what I mean here - see the attachment; A is fine, B is not. (I should be clear that I don't see A as a good actual suggestion to use, it's just good for illustrating what I mean here.)
There's a bit more flexibility with the impact blast - the shape of the blast comes from a graphic file, with only the color being determined at runtime.
Do keep in mind that it needs to be adaptable to high-res, too. The same rules apply to high res, although there's twice as many diagonal lines making up the laser, so it can certainly be more detailed - and it is perfectly fine for the high res one to contain a larger variety of colors than low-res (I'd imagine this would most likely be in the form of "some inbetween colors are used to create a nicer gradient" than outright "it's more colorful", but right now I'm just talking about what's technically feasible more than what's a good idea).