problem with dual wield?

Ok I asked an imm about this, and they thought the same as me so I brought it here. I was under the impression that daggers of similar weights could be dual wielded. Here are three daggers I tried with, and my results. I could dual wield any one of them with a sword that wasn twice as heavy as the daggers (daggers 50% of the sword weight), and that worked. But for some reason I can't dual wield daggers. Am I mistaken in thinking you can dual wield daggers of similar weights? (sorry to be so verbose) You stop using a blessed dagger named 'Heartseeker'. You wield the diamond dagger named 'Light of Redemption'. The diamond dagger named 'Light of Redemption' feels like a part of you! You stop using the diamond dagger named 'Light of Redemption'. You wield a dagger named 'Feathered Death'. A dagger named 'Feathered Death' feels like a part of you! You stop using a dagger named 'Feathered Death'. You wield a blessed dagger named 'Heartseeker'. A blessed dagger named 'Heartseeker' feels like a part of you!