naval weaponry vs arms

naval weaponry and arms both are nouns.

Word	Noun	Adjective	Verb	Adverb
naval weaponry	Yes	No	No	No
arms	Yes	No	No	No

As nouns, arms is a hypernym of naval weaponry; that is, arms is a word with a broader meaning than naval weaponry:

Other hypernyms of naval weaponry include implements of war, munition, weaponry, weapons system.

naval weaponry (noun)	arms (noun)
weaponry for warships	weapons considered collectively
	the official symbols of a family, state, etc.