In the game there is an interesting perk - recover, it allows you to skip a move spending 9 action points, but reduce fatigue in half.
This mod adds the opposite perk.
For 40 points of fatigue you will get + 9 action points, you will get tired faster, but do more, the meaning is that the fighter will fight at the limit of strength, getting more tired.

Can be used to catch up to a retreating enemy, or can be used in the heat of battle to strike an extra blow.
Perk "adrenaline" for 20 fatigue allows you to act first on the next turn, but with rage for 40 you can "lengthen" the current turn, you can consider it a second breath.

Known Bugs:

The game has a limit on action points, if you use "rage" at the start of a move that will give you +9 points, (then you have 18/9 action points) but if you take one step you have 15/9 action points and they reset to 9/9, but if you take 3 steps you also have 9/9 but 4 steps is 6/9, the calculations are always correct, it's just that if at the end of the calculation you have more AP than possible (xx/9) they reset to the normal 9/9 value.

How to solve this - proper management.

Example: If you are standing next to an enemy you can press rage, then you will have 18/9, by doing a two-handed strike you will have 9/9, do another strike and it will be 3/9. And now we act smarter - we make a strike, it's 3/9, press rage, you have 12/9, make another strike, you have 6/9, and the last strike will leave you with 0/9.
Three strikes instead of one, but don't forget that the strikes themselves also spend stamina - you get a balance.

However... you can always change the code and set such values as you want)