The Argentiums, in general, have voluminous amounts of silvery aura that's tinted with their respective natural hue while differing visual effects that match their personalities, combat forms, and any external influences affecting their growth (i.e. "blessings", otherworldly products that were consumed at certain points, Aura-imbued keepsakes, etc).

For example, in Elio's case, when either purposely emitted or keenly sensed by other Aura-sensitive individuals and Pokemon alike, it's likened to "a massive silvery sun eclipsing the nightly heavens above": its radiance and intensity fluctuate with his mood, alluding to both his namesake and his emotional state. When angered, it 'burns brightly' and has 'the weight of the skies' to it - immediately mutilating the surroundings and severely injuring (and in some cases, outright exterminating) those of a 'lower level' should a sliver ever unconsciously escape his person, typically visualized as a plethora of mono-prismatic light-based cues. In his usually tranquil and easygoing state, it 'emits a brotherly warmth' that's so irresistible it's capable of drawing others in, enhancing his natural and potent charisma; the influence of [Y.H.V.H. the Arceus] and [Velek the Zygarde] also gave Elio's aura life-giving properties - stimulating vitality, healing, and growth while deepening his allusions via the sun's association with life itself.

Throughout their entire lives, each sibling is intensely trained to master this ancient worldly power - being their greatest boon and most severe bane; while it's a sturdy foundation for their victorious endeavors, when neglected, the power will steadily destroy them over time - their bodies incapable of containing such a formidable gift. Currently, they've all achieved a certain level of Aura competency that varies between them -minutely exemplified by their various applications and the degree of enlargement of their already massive Aura pool.