Side Smash: Ayra's side smash attack is based on the Myrmidon/Swordmaster normal attack animation in Genealogy of the Holy War and Thracia 776, where she slashes in a downward arc fashion and then in an upright arc fashion.
Up Smash: Ayra's up smash attack is based on a critical attack animation in Fire Emblem: Path of Radiance and Fire Emblem: Radiant Dawn.
Up Special: Angular Swipe - based on a critical attack animation in Genealogy of the Holy War and Thracia 776, where a Myrmidon/Swordmaster would fly horizontally and then vertically when the attack connects. It's a perfect recovery move that combines horizontal and vertical recovery. If Ayra is knocked far away from the stage and above it or jumps under the stage, she would recover horizontally then vertically to grab the edge.
Down Special: Warp Around Counter - based on a critical attack animation in Genealogy of the Holy War and Thracia 776, when a Myrmidon/Swordmaster warps around the enemy before the attack connects. In Smash Bros., as a tradition for Fire Emblem characters, this is a melee counter move.
Pummel: Ayra impales the opponent downward. It will KO at 96%.