Up Air has many uses, but the main two are combo extensions and juggling. It has very low lag and is active for 5 frames, meaning its great for juggling as you'll be able to act quickly and react to their DI, and is good for combos because you can hit your follow-up very quickly. It's also capable of starting combos if you land with it and due to it's range and safety on shield, this is an okay move to land with.
Due to being able to autocancel on SHFF, Uair is one of the best aerials in the game at frametrapping airdodges when juggling. Similarly to Pyra, Mythra can also use Uthrow Uair to setup frametraps once Dthrow stops true comboing
Hitbox Active
FAF
Autocancel
Landing Lag
Damage (base)
Damage (1v1)
Angle
KBG
BKB
Shieldstun
Shield Safety
9-13
31
16+
8
6
7.2
81
60
90
3
-5