You are using a trace, but as far as I can see, the trace in the video is created by the “Fire” instance. The light is either from the part being neon or a light source that is red.
I don’t know how they did it. But I think what you have so far looks pretty good. I think it would look better if you either taper the tail size down or fade to invisible at the end (or both).
They may have have used two, one for the bright white part and another for the red part.
Seems like they have some sort of point light source going on as well, before the projectile is thrown.
Let me explain how it works in the video: so, the player either has to hold or click the mouse button. They have a debounce every .4 seconds so you couldn’t spam fire, then they have a toggle of hands, for example it starts with left arm animation, and you could have a piece of code like this:
local direction = armToggle and “left” or “right”
armToggle = not armToggle
Afterwards, it spawns a sphere with a Fire object inside of it, which is like a particle emitter but fire, and it has a body velocity in it that goes in the char.HumanoidRootPart.CFrame.LookVector direction. Hope this makes sense!