A palladium, or palladion, was an image of great antiquity on which the safety of a city was said to depend that appear in Greek and Roman mythology. "Palladium" especially signified the wooden statue (xoanon) of Pallas Athena that Odysseus and Diomedes stole from the citadel of Troy and which was later taken to the future site of Rome by Aeneas. The Roman story is related in Virgil's Aeneid and other works.
In English, since circa 1600, the word "palladium" has meant anything believed to provide protection or safety, or a safeguard, therefore similar to the word "aegis."
Palladion serves as the initial Persona of Aigis. Her skill set consists of physical attacks and status enhancements. At a specific point in the story, Palladion will become Pallas Athena. By comparing Palladion's cold, mechanical design to Aigis' initial, mechanically programmed personality, Palladion represents Aigis as an android. When Aigis recognizes and accepts her emotions and humanity, Palladion becomes Athena herself rather than a model or representation of her.
Persona 4 Arena
Palladion appears as a laser cannon held by Aigis that she uses as an instant kill. It is known as Heritage Liberator Palladion.
Medium Phys attack that pierces to the back row. (1 enemy) Stronger in Boost.
Light Nuke attack. (All enemies)
Medium Nuke attack. (1 enemy)
Raise defense and protects allies. Extra defense while protecting. (1 row)
Remove stat penalties. (Party)
Medium chance to null Fire/Ice/Elec/Wind/Psy/Nuke damage to user's row.
Medium Phys attack. (All enemies) Stronger in Boost.
Medium Nuke attack. (All enemies)
Lower defense for 3 turns. (All enemies)
Heavy Nuke attack. (1 enemy)
3-8 heavy Phys attacks to random targets. (All enemies) Stronger in Boost.
Revive and restore all HP. (1 ally)
Heavy Phys attack. (All enemies) Stronger in Boost.
Concept artwork of Palladion
Palladion appears in Persona 3 Manga
Concept anime sketch of Palladion in Persona 3 The Movie
Palladion's Persona 3 The Movie concept design
Concept movie artwork of Palladion in Persona 3 The Movie
Palladion in Persona 3 The Movie
Palladion in battle
Aigis using Palladion in Persona 4 Arena / Ultimax
Palladion in Persona Q: Shadow of the Labyrinth
Palladion in Side P3
Apart from her appearance as Aigis' Instant Kill, Palladion also appears as a palette swap for Ariadne when Labrys is using her Aigis palette. This gives her the distinction of being the only Persona in the game who appears as both a usable Persona and as an alternate palette.