A person or thing that disarms; someone or something that removes weapons or makes harmless.
From 'disarm' (from 'dis-' + 'arm') + '-er' (agent noun suffix). This creates a noun for a person or thing that performs the action of disarming.
Military strategists and negotiators could be called 'disarmers'—but the word is so rare that we just say 'someone who disarms' instead! It's another example of how technical '-er' words sound awkward with complex verbs.
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