aver vs attest

aver and attest both are verbs.

Word	Noun	Adjective	Verb	Adverb
aver	No	No	Yes	No
attest	No	No	Yes	No

As verbs, attest is a hyponym of aver; that is, attest is a word with a more specific, narrower meaning than aver:

aver: to declare or affirm solemnly and formally as true
attest: authenticate, affirm to be true, genuine, or correct, as in an official capacity

Other hyponyms of aver include hold, claim, take, declare, protest, assure, tell.

aver (verb)	attest (verb)
to declare or affirm solemnly and formally as true	authenticate, affirm to be true, genuine, or correct, as in an official capacity
report or maintain	provide evidence for; stand as proof of; show by one's behavior, attitude, or external attributes
	give testimony in a court of law
	establish or verify the usage of