Couple of wording points:
1) Better wording for the first ability is: "Response: If Boromir is about to take a wound, exert 2 unbound Hobbits to prevent that wound."
2) For the second ability, you need to lose the response bit - a response action is optional.
Otherwise, very cool card. And power level seems good, especially as you can only start him and 1 unbound Hobbit.
And by the way, I also have a Boromir with that subtitle coming in my next DC set...
Thranduil