Tap the bearer of a Dagger of Westernesse during the site phase at a Ruins & Lairs [R] and play this with the Dagger of Westernesse. Dagger of Westernesse receives +1 prowess (+3 versus Undead and Nazgûl). Cannot be duplicated on a given Dagger of Westernesse.
"No other blade...would have dealt that foe a wound so bitter..."
-LotRIII