"•You deal 2d4 damage with daggers rather than the normal 1d4."
This is roughly similar to the ability to use non-light weapons granted by the Dual Wielder feat. 2d4 damage is only half a pip away from the 1d8 damage a rapier would grant you, and is otherwise identical (they are both piercing, finesse weapons).
"•You gain a +1 to AC when fighting with a dagger in each hand"
This is also similar to the AC benefit granted by the Dual Wielder feat, though specialized slightly in that it only works with daggers.
"•You do not suffer disadvantage for long range dagger throws"
This is similar to the benefit gained from Sharpshooter, but only works with daggers, a mediocre ranged weapon.
On balance, I'd say these benefits are not out of line when compared to the Dual Wielder feat.
Aside from the previously mentioned issue of this feat stacking with Dual Wielder, I'd caution you to avoid too much specialization as a balancing factor. One of the things that caused 3rd edition to get out of hand was the fact that specialization was used as a way to balance abilities; it resulted in the scenario where you were especially good at the things you wanted to do, and especially bad at the things you'd never do anyways.