Blood Weeper is speed 1.8, Avool's is speed 1.5. So, assuming a 0.1 speed improvement (for OH, faster = better) is still worth roughly 10 DPS, the speed difference almost offsets the DPS gain. Add that to the fact you lose the weapon specialization benefits from HnS for your OH, and I suspect you're better off sticking with the sword.
Hard to say for sure, as the stat bonuses are also better on the dagger, and Avool's has a chunk of hit which you may or may not need. As is usually the case, the best answer is to use the spreadsheet, but you may have to manually add a load of your gear if it's not very high level.
@Nocturnal, another dagger would see you speccing into Mutilate, not CQC - you always need a slow, hard-hitting MH for Combat specs. Fist, yes, dagger, no.