1H is more versatile, because you can swap out a spell, shield, or dual wield as needed. IDK from WoW, I tried it, didn't really get into it, a little too cutesy for my taste. Anywhom, Conjuration (Necromancy) 1H, Block, HA, and Destruction (Maybe some late game Enchanting.) Going by the posted description, Cloak (Flame, or Frost, Storm isn't all that great) effects do DOT while you're slugging it out in the melee, so I second the Ebony mail as the armor of choice.
I don't like the Ebony Blade when it comes to actually using it, because you have to work up your 1H to get decent damage out of it (It's a sword, not a Greatsword, which takes up both hands) and then it gives you 2H Xp just because of who it comes from. Gauldur Blackblade, Blade of Woe, Windshear, Targe of the Blooded, and once you start enchanting, Ebony War Axe with Absorb Health, and Firey Soul Trap. (Or whatever, my personal choice.) Hack&Slash is awesom stacked with other DoT effects like On Fire, the targe of the Blooded, Falme Cloak, and the poision damage from the Ebony Mail. Absorb Health, just because, it looks cool, keeps you alive, and adds Moar damnage to your weapon.
Don't do Vampirism, nor the Necromancer's Amulet, their weaknesses don't make up for their strengths.