Indeed weapons in the hands of Gods and Goddesses are powerful not because they are weapons but because they are given that Power by the supreme Shakti, that is, ambaaL. What She is said to do by Her weapons and other instruments is all just Her Will. She wills it and it is done. What a mysterious play! Just catch hold of Her feet. That is enough.
She wills to shower Her Grace and there is a downpour of abhaya (fearlessness), vara (boon), control of the five senses, control of the mind, and what-have-you!. As a cosmic play, She may use Her weapons, or She may not; She may show mudrAs or She may not.