Reinforced is a star within the Constellation The Steed in Elder Scrolls Online.
This was added in Update 6 with the Champion System. When activating a block gain a damage shield for (1216) every 10 seconds. (at VR14). The value of the shield varies per level. 120 points in the Steed Constellation are required to unlock it. Once unlocked the player will acquire this bonus automatically and across all characters on their account.