A item for the offhand slot which generates a shield(absorption)

Whilst playing around in the world an idea struck me like a lightning. The idea is a item which can be equipped like a shield or totem of undying. The item in question generates a small (1-3 hearts) shield which is unaffected by hunger. That means the shield can always regenerate but takes time to do so (like 30 seconds for half a heart). The item itself can be obtained in strongholds or structures from the nether/end cities.