I already posted this in the feedback section, but the best way (In my view) to make their late game balanced would be to make their units and upgrades more expensive. All the different economy upgrades and powers they get means they can make more money than any other faction, so their stuff should cost more too. This is how its handled in BFME1, and that game is extremely well balanced. With full 6 Furnace discount, Forged Blades and Heavy Armor should cost 400 to equip, banners 250, steel bolts 600, and captains 1000. Shield Bearers shouldn't be made more expensive cp-wise, but more expensive resource-wise, with full discount they should cost somewhere around 600 per unit. However, late game is not very problematic, because most people will do their best to shut you down as fast as possible, especially Rohan with their peasant spam. Early game Isengard is pathetically weak. It needs tweaking to both early and late game.