When healing an ally with a staff, grants Def+4 to all allies for 1 turn.
Balm specials are a unique type of special move, being only available on staff-users and providing no sort of direct damage reduction, damage increase or healing. Instead, each provides their team with a stat buff equal to +4 of the relevant stat. Each of the four Balm specials boosts a different stat: Fire for attack, Winds for speed, Earth for defense and Water for resistance. And while the skill description states that “all allies” receive the buff, the user of the skill themselves does not receive its benefits.
Balm specials are the only type of buff that is capable of reaching across the map. In addition, it is a tangible “blue” buff, which means it appears on the stat screen. Balm specials can be used to boost the power of a Blade tome user, or provide a team with buffs that last through an enemy phase. They are great for buffing units who might play away from the team, or on certain maps that split units up into different quadrants. If you pair up the user of this special with a dancer, you can effectively keep the buff active every turn, provided you have two opportunities to heal every turn.
Healers have few choices of special, and most revolve around healing. Considering that staff-users are run primarily to provide healing, it is more likely than not that a healing special will be useful. While the buffs provided are strong, they are not exclusive to healers. Thoughtful positioning can allow a Hone/Fortify skill user to buff all of their allies, without the need to run a healer, or a dancer to maintain it every turn.