An Outlands-friend.
There is the Sword of Morthond but only for Gondor allies. Still, all the bonuses are for Outlands you control, so this wouldn't work across the table as, for instance, the Rohirrim bonuses do.
Sadly, you can't play Nor am I stranger on someone then play mutual accord to let anyone have the Sword of Morthond. That would be amazing.
Incidentally there are a lot of good gondor allies you can attach the sword to, then sword thain them for heroness, elf-friend them and then you have an outlands/gondor/elf hero, all the best buffs except for dwarf.

