How does Starlight Breaker work?
The starlight breaker actually gathers energy from the surrounding area - either left behind by Nanoha herself, or by other mages/combatants.

So it basically works like this:


Gather energy from the surrounding environment into a ball.


Nanoha hits the ball, which fires it.




Typically in a battle, all the mages will leave behind excess energy as a result of using their spells. So the starlight breaker is most powerful near the end of a long battle when a lot of energy has accumulated.



That said, Nanoha is not the only one who can use the Starlight Breaker. Reinforce does it near the end of Nanoha A's - mainly because she gains the abilities of those who's linker cores she has captured.