I would like to see it either remove weakness, or summon everyone to the caster, like a raise. The upcoming damage-immunity change hopefully lasts 2 seconds longer than the raise animation so that people have a chance to to spread out.
Seem too powerful? That's the problem, both DPS Limit Breaks are extremely powerful for their cause, and the tank/healer limit breaks sputter and spew.
You need some sort of limit break on Ifrit (i'm sure a really geared group doesn't, but they don't go to ifrit either). It saves time on Garuda, and is often necessary on Titan's Heart. Why is it not cheesing a fight to build up LB, one shot adds, or take a chunk off the heart but cheesing a fight to pop tank lb and mitigate the damage (which doesn't work most the time, the only life it saves is usually the tank).