The Aigis

The Aigis/Aegis, in Greek myth, was the breastplate ornament passed down from Zeus to Athene when Athene's friend Pallas died. Athene personalized it using some Gigante-skin and Gorgon-heads and ta-da, the aigis aqcuired the power of paralyzation to any who beheld it! Although constantly depicted as a breastplate ornament in their art, the Greeks would sometimes call it a shield (hence the modern confusion over the whole "shield or breastplate ornament" thing).
Okay, I've been trying to figure out why the aigis is sometimes confused as a shield. But then I just figured it out! The Greek "apsida" meaning shield, doesn't actually mean shield, but buckler, which isn't always meant to mean shield, but sometimes just an unspecified form of protection. So when the Greeks called the Aigis an "Apsida" they must've really meant some form of protection, which makes sense since the Aigis has a paralyzing power.