antagonist vs duellist

antagonist and duellist both are nouns.

Word	Noun	Adjective	Verb	Adverb
antagonist	Yes	No	No	No
duellist	Yes	No	No	No

As nouns, duellist is a hyponym of antagonist; that is, duellist is a word with a more specific, narrower meaning than antagonist:

Other hyponyms of antagonist include dueler, duelist, dueller, enemy, foe, foeman, opposition, Luddite, withstander.

antagonist (noun)	duellist (noun)
a drug that neutralizes or counteracts the effects of another drug	a person who fights duels
a muscle that relaxes while another contracts
someone who offers opposition