I think DI definitely has some great points. What you want is maximum direct wounding for Arwen by way of
Elven Bow,
Rohirrim Bow /
Rider's Bow and
Horse of Rohan (and a
Brego instead of
Asfaloth) so that each of your companions has the mounted exertion text. The best Éowyn for you is
Lady of Ithilien (due to her wounding text and simple amazingness) and so it might be worth packing some healing for her like
Farewell to Lorien. Once you have all your guys mounted, you want
Riding Like the Wind and 4x
Hamstrung with 4x
Final Shot so that you're going straight for a fast win. With all your direct wounding (you might want to splash some cards like
Nocked or
Double Shot for this as well) and stuff to take advantage of it, you should be killing most minions but you might want to run some regroup discard (I'm sure
have some of that though I can't remember it right now). Also, if your double moving and want to keep your hand full of skirmish pumps, stuff like
City of the Trees and
Wells of Deep Memory will stand you in good stead.
If you're running
Simbelmyne (though obviously you can't if you're using
Lady of Ithilien, which might be a problem... though you can if you run
Leowyn as well!), there's no reason not to run 4 and there's no reason to have doubles of any unique possession because you'll ALWAYS be able to fetch the stuff you haven't got.
Thranduil