This is my first attempt at a D/D build. This build was made for pvp as a burst build being able to have enough survival (escaping/condition removal) to deal with opponents while also being able to dish out damage.
I have not done enough research to be sure how the stress test nerfs would affect this build but it was designed around mobolizing with air attunement while being able to use fire to burst and stack might then changing to earth or water to continue burst or cleanse/heal respectively.
Edited: new build
Please leave suggestions and changes, thanks!
First things first: My suggestion for that empty trait would be either Pyromancer's Alacrity or Ember's Might. Just so you can either get your combo ready sooner, or just get that extra oomph out of it.
Henceforth I'll refer to Burning Speed+Double Arcane+Fire Grab as "The Combo". Since that's pretty much the core of DD's burst.
Your description of the roles of the attunements are pretty much spot on. Mind you, both the Earth and Air attunements can serve as initiators (RtL+Updraft, or Magnetic Grasp+Earthquake), but air works better transitioning into fire since a successful updraft puts your target in perfect distance for the combo. I normally personally like starting in Air since RtL gives such great gap closure, but starting in earth with Magnetic Grasp->Earthquake -> (Air) Updraft -> The Combo can be more reliable.
One thing you need to consider is the possibility of a whiff. Because really if you can pull off a successful CC chain into The Combo then you've pretty much won most of the battle and all you have to do is clean up.
Traits look good. The only oddball really is your water trait which I'm assuming to be one of your sources of condition removal. I don't personally feel like it's enough. Because aside from that all you have is cleansing wave which is on a 40 second clock.
My personal suggestion: Swap GoEH for Ether Renewal. -10 Water, +10 Earth, Grab Earth's Embrace instead. Then swap Lightning Flash for Armor of Earth (stability on demand). I like Lightning Flash, I've had a good blast with it but I'm not quite sure what purpose it's going to serve in your build aside from maybe extra mobility. Ride The Lightning gives you a good 1200 distance escape. And if there's anything that's killed me fairly often it's Riding the Lightning away and finding myself stuck in place or still crippled. Ether Renewal and Earth's Embrace (stability) solves both those problems.
Sigil of Superior Air is a no brainer as far as bursts go. You want to be very lucky with this build. Also, have you taken a look at those "on weapon swap" sigils? We Elementalists can use those now. You might be interested in the Sigil of Intelligence (100% crit on next strike) or Sigil of Battle (3 stacks of might).
Rune wise, Divinity has been nerfed down to 2% per rune, so you'll net +12% best case, You can look into Rune of Rage (nets you +10% crit damage) along with 5% increase in crit rate with Fury.
Post thoughts, I highly recommend Earth's Embrace as a trait since you're running what would be considered a glass cannon, and that 33% damage redux is pretty much the equivalent of 2.5k HP as far as your build goes at half life. I've had good duels dropping me down to 3 digits and you'll be surprised how much every bit counts.
That's all I've got, hope I helped somehow!