attester vs witnesser

attester and witnesser both are nouns.

Word	Noun	Adjective	Verb	Adverb
attester	Yes	No	No	No
witnesser	Yes	No	No	No

As nouns, witnesser is a hypernym of attester; that is, witnesser is a word with a broader meaning than attester:

attester: someone who affirms or vouches for the correctness or truth or genuineness of something
witnesser: someone who sees an event and reports what happened

Other hypernyms of attester include informant, witness.

attester (noun)	witnesser (noun)
someone who affirms or vouches for the correctness or truth or genuineness of something	someone who sees an event and reports what happened