What if Tanks were designed like Healers?

[Shurrikhan]

Hey remember when upheaval did more damage when you were more damaged?

(Original) Upheaval [Warrior, lv64] - "Deals an attack with 300 potency. Potency decreases as own HP decreases. Potency also affected by maximum HP-increasing effects."
The first part you may recognize from old Spirit's Within. The second part was why Warriors could use Thrill of Battle as an (incredibly minor) offensive tool.

Upheaval has only ever been on Warrior, at least in FFXIV. There have also been no effects since 1.x that deal increased damage as %HP decreases.
The only other two instances of the ability name Upheaval appearing in FF games, as far as I could find, was also on Warrior in FFXI and Marauder in FF:SoP.

So... not exactly a stolen ability.