All of the listed traits could potentially improve as a result of participating in collegial discussions, but specific emphasis can be placed on debate skills. Engaging in discussions often involves articulating one’s thoughts, defending viewpoints, and responding to counterarguments, all of which enhance debate abilities.
However, language skills, such as vocabulary and communication proficiency, may also see significant improvement through active participation in discussions.
Ultimately, the best answer would be debate skills, as this trait is most directly cultivated through the practice of engaging in collegial discussions.