While Brave and Faith can be temporarily altered in battle, they can also be permanently increased or decreased. Using 'Cheer Up' (Squire) or 'Preach' (Orator) repeatedly on a unit will permanently increase their Brave by 1 point for every 4 uses. Similarly, 'Solution' (Orator) will permanently decrease Faith.
Be cautious when manipulating these stats. If a unit's Brave drops below 10, or Faith drops below 3, they will permanently leave your party. Conversely, maximizing Brave (up to 97) and Faith (up to 94) for specific roles can significantly boost their effectiveness. This is a long-term strategy that requires patience but yields powerful results.