Abyssea didn't change a single mechanic of the game. It just made us more powerful by boosting our powers through giving us more of the current "mechanics".
Abyssea didn't give us anything that Reduced/Expelled the 2sec JA/RA Delay. Which is the kind of "Gaming Mechanics" 12 is talking about.
Abyssea just gave us more of what we have, it didn't change any core mechanic.
The closest thing to a "Change in the core mechanics" was them shortening the "Cure Spell Terror" effect you get if you get Cure casting on you engaging/disengaging. Saddly, This was a terrible fix at best and every other spell/ability/action/swing still imposes this "terror" Effect of not being able to move/act/engage/etc.
I had assumed 100% proc of course. It would have to be to be useful. the only random should be you missing or hitting.
addle, Amnesia, Silence, would be decent Debuffs to put on them. Give them 100% Proc rate.
for Addle/silence, have it last ~45~1min on Normal mobs.
For Amnesia, Have it last ~30 Seconds on Normal mobs.
For NMs, Amnesia Specifically, have it last ~3/5 Seconds, Just long enough to stun a TP move if thrown timed right. While this of course might not be worth it to some NINs (some NINs can face-Eat most TP moves with a WHM)... Maybe you're Soloing Sobek or something? Stun Tyrant Tusk this way? Honestly I'm spitballin hypothetical Situations.