signatory vs attestant

signatory and attestant both are nouns.

Word	Noun	Adjective	Verb	Adverb
signatory	Yes	No	No	No
attestant	Yes	No	No	No

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

signatory: someone who signs and is bound by a document
attestant: (law) a person who attests to the genuineness of a document or signature by adding their own signature

Other hyponyms of signatory include cosignatory, cosigner, cosigner, abhorrer, endorser, indorser, attestator, attestor, witness.

signatory (noun)	attestant (noun)
someone who signs and is bound by a document	(law) a person who attests to the genuineness of a document or signature by adding their own signature
	someone who affirms or vouches for the correctness or truth or genuineness of something