Double Slice: Add your Strength bonus to damage rolls made with your off-hand weapon.
Weapon Finesse: With a light weapon, elven curve blade, rapier, whip, or spiked chain made for a creature of your size category, you may use your Dexterity modifier instead of your Strength modifier on attack rolls. If you carry a shield, its armor check penalty applies to your attack rolls.
Agile: This enhancement can only be placed on a melee weapon which is usable with the Weapon Finesse feat. Agile weapons are unusually well balanced and responsive. A wielder with the Weapon Finesse feat can choose to apply her Dexterity modifier to damage rolls with the weapon in place of her Strength modifier. This modifier to damage is not increased for two-handed weapons, but is still reduced for off-hand weapons
So, will taking the two feats along with an Agile weapon allow me to apply my full Dexterity bonus to damage with either light weapon when fighting two-handed?
Yeah they should function just fine. Agile is written without an assumption about Double Slice being taken given most people wouldn't have it.
If that's the best use of your feats.....eh...
(Identity switch)
Well, I'll have the agile weapons and the Weapon Finesse feat regardless, so it's really a matter of a single feat being taken in a Fighter build that will result in an extra 2-3 damage for 2-3 attacks per round. I've seen worse uses - and to be honest, I don't know what else I'd out there.
Also, for what it's worth, our GM has ruled that the benefits of Double Slice also apply to Piranha Strike - due in large part to the growing absurdity of feat taxes.
Not sure if I'd complain about dexterity power attack out of a Sargava book as an example of absurdities in feat taxes. >.>
Of course not - but due to the absurdity of feat taxes across the board, any opportunity to streamline them into something more practical, less complicated and less restrictive is worth considering.