I've got a couple of ideas on how I want to do the Power Attack edge, and was looking for some feedback on it. I've got two ideas, which more or less do the same thing (trading accuracy for power), but go about it in different ways.
Power attack
Any Close Combat Style or Unarmed 50%
Self, Instant
The character is able to sacrifice accuracy for power in close combat. As a free action the character can activate this edge as part of a close combat attack. For every -10% the character takes in penalty to hit, they add +1 to the weapon damage, to a maximum of -50% to hit. The power attack weapon damage cannot exceed the maximum damage die of the weapon. So a short sword with +3 points of power attack damage will deal 4-6 points of damage.
This edge may be taken a second time when the character reaches 100% in their relevant skill. The bonus damage from this edge may now exceed the damage die of the weapon. So a short sword with +3 points of power attack damage will deal 4-9 points of damage. This upgrade costs five advancement points.
Power attack
Any Close Combat Style or Unarmed 50%
Self, Instant
The character is able to sacrifice accuracy for power in close combat. As a free action the character can activate this edge as part of a close combat attack. The character takes -20% to hit on this attack, but if they succeed they increase their damage die for their weapon by one step. So a short sword Power Attack would deal 1D8 damage.
This edge may be taken a second time when the character reaches 100% in their relevant skill. The character now increases the damage die of both their weapon and damage bonus by one step. So if a character with a D2 damage bonus wielding a short sword uses this edge they would be dealing 1D8+1D4 on each successful hit. This upgrade costs five advancement points.