One of those frustrating cards that's mostly dependent on which quest you're playing... The idea is appealing, but as you get further into the game chronologically, it's less and less likely to find an eligible target. That said, you can force it to work if paired with Bard the Bowman (found in the same pack,) Aragorn, or Rivendell Blade. Whether it's worth building around is questionable, but if you happen to be running those, maybe consider trying this out.
Event. Cost: 0.
Action: Exhaust a Weapon attachment to choose a non-unique enemy with 0 . Discard the chosen enemy.
In it smote and vanished, barb, shaft and feather, so fierce was its flight. The Hobbit
On the Doorstep #9. Tactics.
You're forgetting about the Marksman of Lorien. He also has a huge advantage (compared to Bard and the Rivendell Blade) that his effect can be triggered before enemy attacks, so he can save you a defence. — Goggen 81