While working on adding combat styles and signature moves to my combat system, I was trying to figure out how to allow players to combine moves in ways that make sense. An idea I landed on was to divide attacks into four categories: basic, speed, precision and power. Signature moves would tie to a category and moves that share a category can be combined or you can combine a basic move with a move from another category
combat styles and signature moves design journal post.
Speed attacks would be about fitting in as much as possible into 1 action. Having multiple attacks would fall under this category.
Precision attacks would be about hitting the mark. Sharp shooter and improved aim would be precision attacks
Power attacks would be all about the damage. Power attack would be in this category.
I would have a base modifier that could be built on. For example, cleave would fall under basic. The base modifier would be a -2 mod for the first cleave and an additional -2 for every additional cleave attempt. Anybody can cleave using this modifier as long as they drop their first opponent. If someone wanted to specialize in cleave, they can have improved cleave as a signature move. Improved cleave gives them a bonus on their cleave attempt. Depending on character build, a player could use a precision move like flashing blade to reduce their damage to improve their attack or use power attack to improve their damage while reducing their attack.
I feel this setup opens up avenues while keeping things realistic.