Cannon Revolsio weapon potential Delicate Undertaking (yes or no?)

[Du1337]

Wich weapong potential for the Cannon Revolsio should I take?

Epicenter: Range dmg increase 6% on weakpoints

or
Delicate undertaking (Refining Operation in JP server): Increase Power based on DMG dealt, decrease DMG received based on DMG taken, decrease PP consumption based on PP consumed (16% MAX: 1% per 150,000 DMG Dealt / 750 DMG Taken / 250 PP Consumed)

And how does this second potential work? Do I need to deal this on one target or can I stack on more targets? Does this have to be a single dealt of 150k to work or can it be more than one shots?

I'm a bit confused about the second potential.