The correct description is "Defender II Action Cost: 3 Axe Optimal Rank: 48 Requires: Disciplines of War or Magic Cast Time: Instant Recast Time: 30 sec. Tighten your guard, increasing physical and magic defense while reducing attack power and magic potency. Increases enmity generation while under the effect of Steadfast."
Zam is using the old version which neglects Magic Defense, and therefore Magic Attack.