This simple trick will make your characters near immortal, as any damage taken during battle will be healed, given you a great advantage when fighting tough battles.

Just use this combination of Skills, Items and Sealstones:

First Aid (Skill) + Survival (Skill) + Metabolizer (Accessory) [Ring of Healling can be use in the place of Metabolizer] + Lifeforce Blessing (Sealstone).