PvP - Damage Calculation.

Hi all. I have a question here: Does damage calculation work well in Pvp (or maby in game overall)?
I just had a duel with my friend, I'm a 43.lvl dual wielding claw Shadow and I have almost 1800dps with 2.8AS (basically 600+ dmg per strike). We were dueling and I noticed that my char has nearly zero damage output, my enemy has 100~ armor (5% reduction ha?) and I hit him about 100damage. How?? Can someone tell me how 600+ became 100.
It's just that I really like the idea of the dual wielding, I don't wanna use weapon and shield, and already tried 2h Duelist. My friend is Shadow too, but he's already failed at dual style char.. and now he's using sword and shield. We both have 42-43lvl, almost zero armor (less then 100), both have 1300hp. I have 1800dps (Dual Strike) and he has 800 dps (Heavy strike). And? He kills me in 3-6strikes, I'm in 6+ because in some strange logic my total damage 300-900 becomes 100-150, and he's dealing full damage.
Thnx for your time and advice!