I hope they'll be daggers for mage, priests and warlocks. One of the most surprising thing in the online game is when an out of mana cloth-character comes with his 300/300 weapon and beats you.
But I'm confident, as warriors and hunters can also fight with a dagger, I just assume that this one is a rogue ability incrusted in a weapon card.
Protect me from my friends, I'll look after my foes.