So, thinking of the BASH system where everyone gets 10 Energy to represent special stuff they pull during combat...
Special Manuevers: 3 energy each. Choice of stuff like Extra Damage, Extra Accuracy, Extra Attack, Disarm. Gifts often reduce these costs or combine the benefits. ie- Two Weapon Style (while wielding two paired weapons, two manuevers are -1 energy cost. If you take it twice, they all are).
Spells: Minor spells are 2 energy each, major ones are 4. There are some Gifts you can take that reduce these costs.
Energy comes back quickly... you get 1 point per round of not doing anything really strenuous and 2 per round of doing absolutely nothing but recuperating.
Weapon Focus: choose a fighting style. When using it, you can use two special maneuvers per turn instead of just one.
If you use a power that takes more energy than you have, you take some long-term strain instead and are thereafter penalized in that stat.