I think Square needs to find a system and stick with it...

of all I played...

FF4: None if I remember right...
FF6: Wasnt it low HP?
FF7: Cumulative damage(good system)
FF8: Low hp(another good system)
FF9: Cumulative damage
FF10 Cumulative damage
FF10-2: none...
FF12: Use mp?(not that great, but mp isnt that useful in this game so its not bad)

What it does...

FF6: Power attack, half savable I guess...
FF7: Power attack, savable
FF8: Power attack, half savable
FF9: Trance system, which makes you stronger over a period of time, not savable
FF10: Power attack + timing puzzle, savable
FF12: Power attack + timing puzzle, savable

None of them are the same in both...