I don't recommend this. Just throw together your strongest weapons and run a Water team.
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Running your wind team in this event will really hurt you. Even with 0 assault weapons for water, chances are your water team will be better. Since stats are stats, even if you won't get any assault bonuses, your eidolons and the wind weapons still provide atk/hp.
Just use the weapons with the currently highest stats. That'll probably be your Wind weapons? And run with a team of mostly water characters. Obviously you'll need your soul to equip a water weapon.