Horn of Gondor gets a lot better the more players you have, and I think it's just about perfect thematically now. It makes me wish we could get a Leadership version of it that gained resources when an enemy was defeated.
I've wanted a tactics or leadership attachment that generates resource when you kill enemies for a long time now and although we got Sword of Numenor it isn't what I wanted and I hope that we do get a different version of some sort eventually.