Standard sword attacks deal "white" temporary damage. To make it permanent, you must follow up with Claw attacks to deplete the "green" health bar before the enemy heals.
The combat in Thymesia is its standout feature, focusing on a unique "Wound" system: Thymesia-FLT.part1.rar
Corvus can "prey" on enemies to steal their weapons (like spears, axes, or scythes) and use them for a single powerful strike. Standard sword attacks deal "white" temporary damage