knuckle duster vs weapon

knuckle duster and weapon both are nouns.

Word	Noun	Adjective	Verb	Adverb
knuckle duster	Yes	No	No	No
weapon	Yes	No	No	No

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

knuckle duster: (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 knuckle duster include arm, weapon system.

knuckle duster (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