This is a bit difficult to explain. Wall-of-text incoming for the attempt.
Unlike other fragments, particle clouds such as Kytryn plasma pod explosions, seem to move with the player. Other explosions would stay where they fragment, and if the playership moves, the explosion will eventually scroll off the screen. Particle clouds do not do this. Where they are relative to the playership, they maintain their relative position with the playership. If the playership moves north, the explosion moves north with the ship. It is like an overlay that attached somewhere off the ship. Meanwhile, the sticky particle cloud will hurt or kill things as it dissipates.
Sounds like you're talking about hit effects vs. fragment effects. See also Area-effect explosions shouldn't cause large explosion hit effects when hitting unshielded objects.
I do not see the connection with that other ticket. This has nothing to do with decorative hit effects. This is about a destructive explosion attack (fragment) that moves with the player instead of being anchored where it exploded. This does not happen with other explosion fragments like Black Strelkas or true shockwaves like Ares Warhammer. Only particle clouds/shockwaves like Kytryn plasma pods (and mod weapons that want to use particle shockwaves instead of real shockwaves).
Ah, I see. The particles defined in <Missile><Fragment><ParticleSystem> are created with velocity relative to the ship that fired the missile, not the missile itself, the object that's hit, or the system reference frame like most fragments. Weird.
Fixed in 1.8 Beta 1.
We use the ship's reference frame because we want the particles to appear to be shooting out of the ship (e.g., plasma torch). But for fragments, we clearly want the system reference frame (like most fragments).