While running Ruarc in UNCB in the lead position I noticed throughout the entire run his A2 was landing with a 25% DecAtk when everything written up on him shows a 50% DecAtk. 

What happened!?

Rust Consume You (Cooldown: 4 turns)
Attacks all enemies. Has an 80% chance of placing a 50% [Decrease ATK] debuff for 2 turns. Also steals all [Continuous Heal] buffs from each enemy. This effect cannot be resisted.
Level 2: Damage +10%
Level 3: Buff/Debuff Chance +10%
Level 4: Buff/Debuff Chance +10%
Level 5: Cooldown -1
Damage Multiplier: 3.3 DEF