Quote:
This entirely depends on your level and your dual wield skill. As a general rule, you should have your faster weapon in the secondary for dual wield skillups and more offhand swings. However, once you reach a certain level (somewhere around 50) your DPS is better off with a fast weapon in your primary and the best ratio in the secondary.
Your duel wield skill will max out regardless, to remove confusion, just the best ratio'd weapons you can find, and stick the faster one in your mainhand. Main hand damage bonus equals 1+(level-25)/3 if I remember correctly.
As a rogue, when you hit your mid 50's you will be looking for a high damage piercer to put in your mainhand, as backstab will start become a decent percentage of your total damage.