I like the new idea of weapon mastery in DnD Next…let’s expand on that…
Double accuracy
Feat
Benefit: You use a reroll of a die give to you by your weapon mastery power and roll the same number on both dice rolls, consider the rolled value equal to the maximum of the die type.
Thoughts?
Throat Punch Games 
It’s great for when you get those double 1s but you’ll wish it did more when you get those double max.
What about having it add half the maximum of the die type so that then it would have an effect every time you rolled a pair? Example rolling a d8 get two 1s would = 5 two 8s would = 12. Granted it’s not as much of a damage differance but it doesn’t have that feel bad when your rolling high pairs already.