Blade of Secrets

Those struck by this blade find their arcane knowledge stolen.
Pick one of the bearer's melee weapons to be a
Blade of Secrets. Allocate wounds inflicted by
that weapon before allocating wounds inflicted
by any other attacks made by the bearer. If 1 or
more wounds are inflicted on an enemy
WIZARD by that weapon, pick one spell that
WIZARD knows. That WIZARD may not
attempt to cast that spell again during that battle.