The word "more qualificatory" essentially refers to something that adds more weight or value to an argument or statement. There are many synonyms for this term including substantiating, corroborating, supporting, and validating. These words all refer to providing evidence or proof that reinforces an idea or claim. Other synonyms include justifying, vindicating, and endorsing, all of which imply that something has been approved or validated by someone in an authoritative position. In short, any word that suggests adding credibility or strength to an argument can be considered a synonym for "more qualificatory".