Okay, I'd like to say that this is a little bit overpowered, but it's interesting.
I would like to propose a change in the way it works.

first of all, I'm not sure if you noticed but the sprites between falling and jumping (or flying and free falling) make a decent animation for wing usage

also you could make it work sort of how birds fly

there would be 2 major phases
the flight
the glide

the flight would work like unlimited jumping but would drain a little (VERY LITTLE) energy for every jump
the glide would be mouse controlled (like the flight is right now) but with a very slight drop rate and energy can recharge in that period (or not, it's your choice). That way you give a mechanic to fight in the air and not having to go straight to your oponent