weakling vs someone

weakling and someone both are nouns.

Word	Noun	Adjective	Verb	Adverb
weakling	Yes	No	No	No
someone	Yes	No	No	No

As nouns, someone is a hypernym of weakling; that is, someone is a word with a broader meaning than weakling:

weakling: a person who is physically weak and ineffectual
someone: a human being; person, singular, assertive existential pronoun; pronoun, person, singular; quantifier: assertive existential

Other hypernyms of weakling include individual, mortal, person, somebody, soul.

weakling (noun)	someone (noun)
a person who is physically weak and ineffectual	a human being; person, singular, assertive existential pronoun; pronoun, person, singular; quantifier: assertive existential