Level 5: Noble Courage - The First under the King's banner were a source of inspiration and courage. Allies in the vicinity of the Palace Guards of Arnor gain experience more rapidly. (Passive ability)
The Arnor Palace Guards have access to the following upgrades:
Banner Carrier - This upgrade can only be given to a level 1 battalion and will promote it to level 2. At level 2 the battalion can regenerate units when out of combat. Cost: 200
Heavy Armor - Increases the armor, hit points and damage resistance of the unit to ranged damage. Changes the unit's armor set to EdainInfantryHeavyArmor. Cost: 300
Forged Blades - Increases the damage of this battalion and provides a damage bonus against other infantry (swordsmen, pikemen, archers, etc...). Cost: 300
Sword of the Westerness - Makes the unit invulnerable to FLAME, MAGIC, FROST, POISON and FORCE damagetypes and increase their damage by 50% against ringwraiths, Karsh and Wights.
Palace Guards are the substitutes for Dúnedain Soldiers in the Arnor mid to late-game. They cost 300 resources more than the Soldiers do, but they are a lot better combat-wise, and when they reach level 5, they unlock a useful support ability that helps other units to reach maximum level.