Silence
Silence is often the best manifestation of wisdom. The wise do not try to convince others and win arguments. They speak only where there is benefit, and not out of self-protection or self-promotion. They believe it is better to lose in debate, than lose integrity.
The ability to argue convincingly, with impressive articulation and captivating delivery skills, does not make one wise. A skillful debater may be very entertaining, much as a champion boxer - but does this make him right?