Arwen Undomiel is an incredibly powerful ally. Two resources for two willpower, an extra hit point, and a very good ability all wrapped into one Magali V. masterpiece. I suppose the only downside to Arwen is that you can't also play the incredibly powerful hero Arwen, but uniquness conflicts are what the game is all about, right?

Rivendell Bow is effectively one of two things: 1) a less expensive Dunedain Cache that only attaches to certain characters or 2) for characters like Legolas or Haldir, a non-restricted attack boost. So while Rivendell Bow may not be the strongest weapon on the block, it is certainly a very good one.

Watcher of the Bruinen is a card I've never really use much, probably due to Tactics' card draw deficiency. He is however, still a pretty good card despite the fact that if he's taking so many attacks, he'll probably be destroyed. He does synergize with the Noldor stuff like Mithlond Sea-Watcher, but the only Tactics Noldor hero is Elladan; who mandates some version of Elrohir. Still a good card.

Watcher + Raiment of War can be an excellent defensive combo. You can get a lot of mileage out of 3 defence and a followup 2 attack in most quests. —

Grave Cairn is very thematic, but suffers from the problem that if a character is leaving play, it probably has low attack. The only in-sphere options that are possibly worth it are the Dwarven Sellsword and the Greenwood Archer. Of course Grave Cairn fits well into a gimmicky deck that tries to sneak attack Gandalf a lot or make frequent use of Reinforcements.

Aragorn is one of the most fundamentally powerful heroes in the game. The ability to pretty much make threat a non-issue is bonkers, especially when you throw Desperate Alliance in the mix (this will also prevent your friends from shredding you when you play Deep Knowledge). Aragorn here is a good quester if you can get Sword that was Broken or Celebrian's Stone on him. He's a two/five sentinel defender with natural access to Burning Brand. He's even a good attacker. Or you can go the triple Unexpected Courage route with all of his toys and turn Aragorn into a one-man Last Alliance.