weather
Rain slows down your parties advancement as well as your enemies, it effects classes riding Nomad horses less but it still slows them down. Usually the rain doesn't last too long in battles but it is enough to annoy you, especially if you are in a race against an enemy or time.
Fog cuts out vision and it only really effects you, this can be easily countered by using constant torches and torch staffs as well as theives but as it is limited to not seeing the whole battlefield it gets really annoying, especially when you're fighting a hard battle with enemies constantly popping out attacking your party and once your reach the village, the village was crushed by an unseen bandit. Fog is permenent in battle until the battle ends.
Darkness is alot like fog, nothing much different, can be countered by theives and torches.
Alot like snow but takes effect on all units, can be countered by going indoors. The snow usually doesn't last long in battles either, but it comes out constantly after turns.
Not really weather but still takes effect on all units. It blocks magic out from all units inside the seal area, even if you are aiming outside of the seal, this is a double-edged sword, you can easily counter this by using physical units instead of magic units. Usually if you attack Kishuna, him and the magic seal will disappear, usually you wouldn't want to do that if the battle is in you're advantage but sometimes you have no choice but to, to finish the chapter.
