Shields offer protection by absorbing incoming damage, letting only a fraction of the damage through. The portion of damage blocked is equal to its Defense; shield bypass effects reduce this value multiplicatively.
The amount of damage a shield can sustain is equal to its Shield Energy. Any damage blocked takes away from this statistic, subject to resistances. Upon complete depletion, the shield ceases to function until the next combat. Shields fully recharge at no cost between each battle.
It is important to note that resistance has no effect on a shield's Defense value, as well as the portion of damage dealt to health through the shields; it only reduces the damage that the shield takes from the portion of damage absorbed.
Some shields have a Shield Recharge ability, which enables the shield to regenerate after a certain Recharge Delay has passed since last taking damage. Shields cannot recharge after being completely depleted. When using the Regeneration Converter special, if the equipped shield has the Shield Recharge ability, the shield's Recharge Delay prevails.