I have a glass dagger in one hand and chillrend in the other. Glass dagger so I can do 1hit backstabs and sword in other to increase double power attack damage and use in face to face combat as main weapon.
On my ninja I have a dagger in my right hand and Fury in the other. Dagger helps in silently taking down a single foe, while Fury helps create confusion and thin the herd when there are many enemies in a room.
Mehrunes razor in my offhand and dragonsbane in my main hand, you should always have a dagger in your off hand to increase your dual standing power attack speed.
Dagger in the left, Tomahawk (war axe) or War Club (mace) in the right.
Apache style.
I wish you could parry with your left weapon, that would be sweet. I'm aware this isn't dark souls, but it's still a neat idea to give some sort of dextrous defensive ability to dual wielders.