"Brandishing" is a pejorative term, with an almost universally negative connotation.
If I legitimately believe I am in imminent danger of serious physical harm and I draw my weapon, that is not "brandishing" - that's making ready.
If there is a bunch of punks outside my store hassling customers and I walk out to chase them away with my gun in my hand, that will probably be considered "brandishing."
Those aren't absolute definitions, just reasonable examples. See the difference?