Well I think Balin Runes or at least the DMG Boost ones can beo nly for the Appropriate Heroes like Thorin II and Dwalin,and amy be Fili and Kili as all of those 4 are Strong and Tought wel ltrained Fighters!
As for "Iron Determination" it does sound good,but I think there may be only Dain and Thorin III and Murin should get them or may be even only Dain and Thorin III!
My point is that not all Heroes shiould get such good DMG adn Area DMG boosts but only the strongest and most skillfull fighter like Dain,Thorin II,Dwalin,Balin,Thorin III and Murin!
But I really feel that at least Dain as LEader and arguably the most Important and and Best Dwarven Warrior of the Third Age and may be all Time should get some little boost to make him even to his Cousin!
Greetings!