These unlock more special moves which can be assigned to button combinations or can be used to increase proficiency with specific weapon types. (nextgengamingblog.com)
As I played through the story, more special moves became available that were vital to defeating some of the tougher and more challenging enemies that appeared. (thekoalition.com)
With some upgrades this can also be charged up to do more damage over a larger area at the cost of more special move charges. (iheartinfinity.com)