You shouldn’t be able to heal KO’d members using potions, most likely a little bug slipped in. Will fix it.
I reckon I just missed to hook up ReduceHP and/or ReduceMP function when Moves are used. Will take a look at it and fix asap. (Berserk skill itself just changes a boolean variable in CharacterBattleStats, while it is true, characters basic attacks deal more damage)
I didn’t think about it, but it makes sense to “heal” character up for the amount the maximum HP/MP increased, especially when leveled up. Will add a little function to change it.