It didn't. It kept the same formula from the PSP games, which is real nice. Dissidia introduced a new mechanic in fighting games, and I'm glad that the same mechanic is back.
It's a bit more complicated because bravery can be affected by many variables, such as equipment, accessories, BRV attacks and breaks.
Breaks are when your bravery takes damage until it becomes lower than 0, in which stage bravery is transferred to your opponent and you cannot do damage.
Meaty attacks are timed but give off the maximum damage. Metered attacks give a extended damage while the use of meter, some cases that it has invincibility start up frames or frames in general.
Dissidia uses two kinds of attacks: Bravery and HP attacks.
Bravery is a value that determines the base damage of what your HP attacks can do (you can find that in the video, it's the huge violet-colored numbers that are at the bottom of the HUD). HP attacks have no damage themselves; they rely completely on your current Bravery value. Bravery attacks are used to "take away" Bravery points from your opponent. When your Bravery attacks connect, how much Bravery they lose is the exact same amount of Bravery that you gain. Bravery attacks however, cannot be used to reduce an opponent's HP to 0. That's where HP attacks come in. The only way to reduce your opponent's HP is to use HP attacks.
Yup, they retained it pretty much. And also the "dramatic progressive action" style of combat. Fighting games that have full three-dimensional combat really interest me a lot. I honestly prefer Dissida over sidescrollers (e.g. Tekken)