So what is that "Triangle Lv1" option? As somebody who can't read, write or speak Japanese I shouldn't even try, but here goes...
Transcription:
烈攻斬り
This reminds me of the Japanese for Cloud's "
Cross-slash" limit break:
凶斬り
With Cloud spelling out the character "凶" when he executes Cross-Slash, but this remake footage calling it "烈攻斬り", does this mean that this is merely the Lv.1 version of Cross-Slash? Perhaps when all three limit bars are filled, you get a Lv.3 limit break and it gets renamed to 凶斬り.
This would make the Triangle button your "Limit Break" button.
EDIT: I speculate
even further that since the Limit Bar consists of three bars here, and the ATB bar having three bars on top, you deplete more ATB bars the higher the level of the Limit Break you use.