The heck with hit. GET EXPERTISE CAPPED! And feel free to exceed 26 expertise a little.
For normal 1 weapon tanks, 26 expertise eliminates the chance the boss will dodge your attacks, and reduces the chance the boss will parry your attacks. If a boss parries your attack, it's next attack is hasted.
Having two weapons, this happens twice as fast. You don't need twice the number of faster attacks coming in, so you need to stack expertise so that few (if any) attacks get parried, and therefore increasing your survival.