If you feel yourself losing a lot, I suggest getting rid of the Aether portion of the deck entirely. You don't need it that much at all; it's just there for flavor. A very fast and sound deck can come from a mono-Dark.
For your mono-Dark, ditch the Short Sword, 1 or 2 Steals, a Drain Life if you want, and all the Aether cards (this is all from your original deck). Add maybe 5 Obsidian pillars, an Eclipse, and a couple more creatures if you have room. Go for exactly 30 cards.
Good luck.