What is the collective noun for arms?

There isn't a single, universally accepted collective noun for "arms." However, depending on the context, some possibilities include:

* An arsenal: This is the most common and generally accepted collective noun for a collection of weapons.

* A cache: This refers to a hidden store of weapons or ammunition.

* An armory: This is a place where weapons are stored.

* A battery: This is a group of artillery pieces.

* A brace: This refers to two weapons, particularly pistols.

The best choice depends on the specific meaning you want to convey.