RESOLVED: Jump to end of this post for the resolution.
I have this equipped on one of my creatures, which does “paralyse” a person when hit as a result of the On Hit “Hold” property…
My question is, where is the script fired from? (Or is this a hard-coded application of the effect?)
The VFX for the effect remains for a few seconds after any potential respawn of a victim and I was aiming to find a way of removing that at time of respawn.
Currently, my own function to remove the VFX fails, as no “effects” are detected, including visual ones, even when one clearly is present. 
PRIOR RESPAWN
AFTER RESPAWN
EDIT NOTE:
There are three ways to implement a monster “On Hit” routine:
It appears that the “OnHit” and “OnMonsterHit” may be hard-coded, whereas the “OnHitCastSpell” points to iprp_onhitspell.2da, which, in turn, does point to a script that we can edit.
OK, so maybe the other two are “old” ways of implementing some effects? 
RESOLVED THIS WAY
Backed with the principle that I could edit scripts when using On Hit Cast Spell, I used my own script and applied the script via the other newer “On Hit” property instead.
Works a treat 
and a note to self: try to do all On Hit properties this way from now on, I guess.
