Dark Knight is broken.

[TouchandFeel]

snip

I don't really feel that the core of Dark Arts needs to change that much, that part is fine as is. The problem that I see with it is the way it synergizes with and affects other abilities. Like I said, +140 pot is just lame and a missed opportunity to do something cool with additional effects to abilites from Dark Arts usage.
I go into the kind of stuff that I would like to see or think would help with this in a rework thread I made a little while back.
http://forum.square-enix.com/ffxiv/t...od-Dark-Knight

You do touch on an issue that has been bugging me more and more as time goes on. DRK has virtually no real burst window. To me this is a problem because it leaves DRK with no good way to take advantage of party buff windows like Trick Attack, or at least nowhere near the extent that WAR or PLD can. That just doesn't sit right with me. That and it also leaves the game-play of DRK a tad flat, like you're never really building up to or preparing for something. It's too consistent. Hopefully the devs will be able to figure out a way to give DRK a real burst window and cycle when they do a rework while maintaining a uniquely DRK feel to it.

Off the top of my head here is a little variation of an idea that I had before on how to do this.
Create a way to "store" Dark Arts usages where if you press the DA button again after activating it but not consuming it with an ability, it "stores" that usage as an "Abyssal Shard" (or whatever) that appears on the gauge UI sort of like WHM Lilies which could then boost the effect of the next DA that gets consumed by an ability, such as doubling the potency increase from the DA.