Blocking is actually an interesting topic!
First of all, this game is made in the pico-8 fantasy console, which has (close to) the same number of controls as the NES: you only have a d-pad and 2 buttons per player. so, with a jump and attack button, i've already run out of buttons "^ ^)
Second, if i do figure out a good way to bind it (perhaps as jump + some aim?), i'd rather add a parry, like in Rivals of Aether; a block you'd need to time correctly, basically.
Thanks for your input!