Pyra's Aegis Sword is uniquely asymmetrical, referencing her status as the weakest aspect of the three. When active, it sprouts a large blade of flame.
Mythra's Aegis Sword is symmetrical. When active, it opens up and sprouts a large photonic energy blade from its center, as well as four smaller ones.
Pneuma's Aegis Sword is also symmetrical. While its color palette is simple, its design is very intricate, and its energy blade is huge compared to even Mythra's version.