stun gun vs weapon

stun gun and weapon both are nouns.

Word	Noun	Adjective	Verb	Adverb
stun gun	Yes	No	No	No
weapon	Yes	No	No	No

As nouns, weapon is a hypernym of stun gun; that is, weapon is a word with a broader meaning than stun gun:

stun gun: a weapon designed to disable a victim temporarily by delivering a nonlethal high-voltage electric shock
weapon: any instrument or instrumentality used in fighting or hunting

Other hypernyms of stun gun include arm, weapon system.

stun gun (noun)	weapon (noun)
a weapon designed to disable a victim temporarily by delivering a nonlethal high-voltage electric shock	any instrument or instrumentality used in fighting or hunting
	a means of persuading or arguing