Ether Defence is a stat which reduces the amount of damage received from ether attacks.
Characters' Ether Defence
The damage that characters receive from ether attacks is reduced by the amount of their ether defence. An ether defence of 1,000 will reduce ether attacks by 1,000 points of damage.
If ether defence is greater than or equal to the attack's ether damage, the character will receive only 1 point of damage, or 0 if they block the attack.
Enemies' Ether Defence
Unlike characters, an enemy's ether defence stat is a percentage and has a direction. Ether attacks from that direction will have the damage reduced by the specified percentage. The enemy's ether defence in other directions is zero. Most enemies have an ether defence of zero in all directions, and receive the full amount of damage from ether attacks unless the attack is blocked.
For example, the Blizzard Belgazas has an ether defence of 30 to the front and rear, which reduces ether damage from those directions by 30%, while ether damage from the sides will not be reduced.
The Ether Def Down debuff will reduce an enemy's ether defence by the specified amount. If the result is less than zero, the enemy will take extra damage from ether attacks. For example, if Blizzard Belgazas is hit by an Ether Def Down of 25%, its ether defence to the front and rear will be reduced from 30 to 5; its ether defence to the sides will be reduced from 0 to -25, causing it to take an extra 25% damage from ether attacks on its sides.