I'd like to point out a few issues that no one or I have rarely seen people point out. The DRK rotation forces you to double weave for optimal damage. I don't have a problem with double weaving since I find it fun and skillful ( ping issues aside ). However:
-> In order to mitigate you have to press 3 buttons ( TBN + Oblation + Dark Mind / Shadow Wall ), I would certainly wish for 2 buttons. TBN should have Oblation within itself. The reasoning here is that if you have your burst coming up and you have to mitigate, you have to sacrifice damage to do so ( raid buffs ). GNB solves this problem well because it never forces you to double weave for 6 GCDs straight while bursting.
-> Dark Mind shouldn't be only magic damage reduction please. It can be a lot of things. 10% of each damage reduction and a heal over time, or a heal which converts some DarkSide into HP.
-> Blood weapon shouldn't be tied to duration. It should be stacks because stacks allow you more flexible usage ( ex: Opener, pop it a few seconds before combat starts )
-> TBN shouldn't be tied to damage and MP. Dark Arts could give a free use of something else ( like Dark Mind , a heal ). There's many moments when when you have to burst in your rotation and you have ~4500 mp wishing to use an Edge/Flood within raid buffs, but there's a tank buster coming.