Nihil

Nihil is a skill that prevents enemies from activating any of their skills, except their own Nihil. This works both ways, as your character activating Nihil can protect from the Black Knight's Eclipse, but it can also be used by enemies to prevent Ike's Aether, Tibarns's Tear, and other powerful skills. For any characters who is dependent on high skill activation or use of skills, one should be wary of enemies with Nihil equipped.

In Fire Emblem: Radiant Dawn, the Mantle skill gives its user innate Nihil.

This skill is named Awareness in the Fire Emblem: Seisen no Keifu and Fire Emblem: Thracia 776 fan translations.