It's spawned via effect animations (ie, for instance, the star-shaped explosion when you fire your gun or the "Level up/down!" caption when your weapon level changes.)
As far as I know, this is never called in the game. Out of curiousity I'll comb through the code tonight to see if it's ever called. To use it, you'd have to modify the game's code to call it explicitely. It would be possible to create a TSC command that simple spawns this effect animation when called (or better yet, takes a position and an animation ID, and spawns it) but without resorting to assembly, AFAIK there's no using it.
The ID of the effect is something like 14 or 15 (not 100% sure, and I can't check right now.)
An entity that can spawn any animation effect via ANP commands would be useful. I'll post a script for that once I get my internet access at home back.