jodyjohnson
Adventurer
Each campaign or game is different but it is pretty common to end up with a campaign flow that often has only a single encounter per day. In these scenarios, the Fighter feel lacking in comparison to the classes that can nova usually because they have strong Daily powers. I'm especially noticing this in the 0-2 encounter days of travelling in the Underdark for Out of the Abyss.
Fighter added ability.
3rd level: "Give it your all": You push yourself just short of exhaustion as you give 110%
. Your weapon attacks do an additional +1d4 damage of the same type until the next time you roll initiative. This ability refreshes after a long rest. You may also add this die to Athletics or Acrobatics checks. (Optionally, I could see this imposing a level of Exhaustion like Frenzy for the Berserker and then not limiting to 1/day. It would have a natural limit.) It increases to +1d6 at 8th level, +1d8 at 13th, and +1d10 at 18th.
Note: I do house rule Sharpshooter and Great Weapon Mastery to remove the -5/+10 abilities. So I see this as a small compensation for removing a main source of damage adder for fighters.
One side effect would be to bring two weapon fighting up a notch for one encounter per day. It would also serve to even out the damage curve for Fighters that otherwise has large jumps at the Extra attack levels. Plus the bonus to Athletics and Acrobatics would help bring the Fighter back as a Grappling (etc) specialist vs. the Expertise classes.
If this is too much I could see a more even jump of +1d6 at 13th only.
Fighter added ability.
3rd level: "Give it your all": You push yourself just short of exhaustion as you give 110%

Note: I do house rule Sharpshooter and Great Weapon Mastery to remove the -5/+10 abilities. So I see this as a small compensation for removing a main source of damage adder for fighters.
One side effect would be to bring two weapon fighting up a notch for one encounter per day. It would also serve to even out the damage curve for Fighters that otherwise has large jumps at the Extra attack levels. Plus the bonus to Athletics and Acrobatics would help bring the Fighter back as a Grappling (etc) specialist vs. the Expertise classes.
If this is too much I could see a more even jump of +1d6 at 13th only.