The 15% Attack Speed Increase from the Ethereal Dagger for Wizard is not increasing attack Speed.
How are you determining that the attack speed increase isn’t working? Remember, an attack speed roll on a weapon influences the base attack speed of the weapon, which then gets multiplied by your other bonuses to attack speed. Weapon attack speed rolls are calculated and shown differently than other attack speed rolls.
The base attack speed for a dagger is 1.5. Wizardspike (the ethereal dagger for wizards) has an attack speed ranging from 1.68 (with 12% attack speed) to 1.73 (with 15% attack speed).
1.5*1.12 = 1.68
1.5*1.15 = 1.725
In these pictures, notice the attacks per second line below the damage numbers.
It’s working fine.