knuckles vs weapon

knuckles and weapon both are nouns.

Word	Noun	Adjective	Verb	Adverb
knuckles	Yes	No	No	No
weapon	Yes	No	No	No

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

knuckles: (used in the plural) a small metal weapon; worn over the knuckles on the back of the hand
weapon: any instrument or instrumentality used in fighting or hunting

Other hypernyms of knuckles include arm, weapon system.

knuckles (noun)	weapon (noun)
(used in the plural) a small metal weapon; worn over the knuckles on the back of the hand	any instrument or instrumentality used in fighting or hunting
	a means of persuading or arguing