Dont look for a new dagger, your dagger is fine. It has LOH and a socket, and it is a dagger, which is perfect for now.
Edit: Found out this is a new dagger; nice buy
What you should replace is your main-hand. You want to find a mace which luckily for you is the cheapest option. The reason for this, is that run like the wind tornado's damage is based from main hand damage only, thus you want your slowest/highest raw number damage item in your main-hand.
These tornado's are your main source of damage; they are much stronger than whirlwind or bash, and thus are your priority.
However you also want one with LOH. LOH is more important than how much damage you get on your weapon. If I were you, I would look for a mainhand mace with 650+ LOH. Any stats on it are a plus. Make sure you don't get something with attack speed bonuses, since similar weapon DPS numbers without ias, will actually be stronger.
Also you aren't strong enough gear wise (defensively) to be running a double whirlwind build in A3. I recommend getting your LOH mace, and then trying this build http://diablo.incgamers.com/forums/s...lish-ALL-acts)
You really need 2 defensive passives for your gear level, instead of weapons master.
If double whirlwind build is what you want to be doing in A3, this will get you there and has the same type of gear.
Here is my profile, I have cleared inferno with that gear/build
Hope it helps