Prophetic Strike (Combat)

When you imbue your weapon with arcane energy, you can expend divination power to detect your targets' weaknesses.

Prerequisite(s): Arcane Strike, Spell Focus (necromancy), eldritch knight 1

Benefit: When you activate your Arcane Strike feat, you can expend an unused divination spell that you have prepared or a spell slot of a level in which you know at least one divination spell (for spontaneous casters). If you do, each time you successfully damage an opponent with an attack until your arcane strike ability ends on your next turn, you become aware of one weakness the creature possesses (such as an energy vulnerability or the type of weapon that bypasses the creature's damage reduction) per level of the illusion spell expended.