Great ally for a trap deck! If the enemy doesn't have an attachment, he acts like a Mablung for double the price, but still dealing two damage. However, the best usage is when you can snag an enemy with an attachment, hopefully knocking them out in one blow. As already stated, traps are the first thing that come to mind, but since it doesn't say "Player" attachment, Faramir is not limited to that!! My favorite is using him against Easterling enemies with all their annoying attachments to sock them right in the face! Another possibility could be Nazgul enemies, although those will be harder to take out with the four damage. Okay, not the best stats (one less attack than Haldir of Lórien, and no ranged/sentinel) and expensive for lore, but his ability, while situational, is really fun to use and can be really effective! Sneak Attack is also an option (huh, he's like an aspiring Gandalf ;)
Faramir
Gondor. Noble. Ranger.
Response: After Faramir enters play, choose a non-unique enemy in the staging area. Engage that enemy and deal 2 damage to it (4 damage instead if it has an attachment on it).
-The Two Towers
A Shadow in the East #5. Lore.
I've found this version of Faramir a good companion for Guarded (Enemy) attachments. It is not the best card to deal with them, I agree, but I believe his ability is worth enough to give it a shot.
Once you play the attachment and the guardian is revealed, you can play Faramir to immediately engage the enemy, dealing it a direct 4 damage. If you are able to prepare the encounter deck for this, you will be able to claim the attachment at the same moment you've played it.
It is a bit tricky to make it work, since you will need to have the ability to play both Faramir and the attachment within the same planning phase. On top of that, having a scrying tool, to be sure that Faramir will be able to insta-kill the upcoming guardian, is also a must.
Fortunately, Faramir belongs to the sphere with the most powerful scrying cards (Denethor, Henamarth, Risk Some Light, Rumour from the Earth, etc.). Besides, the lore sphere also has Glamdring as guarded enemy attachment, and there are also available several neutral ones (Necklace of Girion, Ring of Thrór, The Arkenstone).
So, if you are playing with a mono-lore deck, to be prepared to apply this combo shouldn't be as hard as it looks.