The Hidden Benefit of Armor

Last night, I got my Saronite Plated Leggings. I've long been a supporter of armor in order to increase survivability, and part of it has to do with a hidden benefit that doesn't show up in the EH calculations. For those of you unsure of the lingo, "EH" is effective health, which is the amount of health we have, adjusted for armor. It is used to model our time to live in a "worst case scenario" in which we do not avoid any hits. There is some debate about whether or not to include block value on a block-capped paladin in this number (for various reasons), though for the purposes of this post, I will not.

It would seem, then, that a 2% reduction in incoming damage and a 2% increase in armor are the same, are they not? For example, let's say I increase my armor in such a way that I move from 50% mitigation to 51% mitigation. I've reduced my incoming damage by 2%. My other option is to increase my health by 2%, say from 30k to 30.6k health. It would seem on the face of it that there really is no decision to be made here. In one case, I increase my EH by reducing all incoming damage by 2%, while in the other case, I increase my EH by increasing my health by 2%. My EH goes up at the same rate in either case.

However, armor provides a hidden benefit that isn't normally considered: it increases the value of all healing. Why is this? Let's say that I choose the armor over the health. Now, when I am healed, I am healed for the same amount of health. However, I am actually healed for 2% more effective health, because each of my points of actual health are worth more effective health. My effective health is my actual health multiplied by my armor benefit. When my armor benefit goes up, my actual health is worth more EH, and so every heal is actually worth more EH.

Therefore, in a physical damage fight, armor can be considered not only as a bonus to our EH, but also to a bonus to our healing. In fact, the effect of 2% more armor reduction is exactly the same as a 2% increase of actual health plus a 2% bonus to healing. This hidden benefit is why healers find us easier to heal as we gear up. If we were simply increasing our stamina as we geared up, it would take just as much mana to heal us, even if we died less quickly. However, because we increase our armor, the heals our healers put on us are actually worth more EH than if we were simply to increase our actual health.

Armor does have a few problems. It is over-budgeted, in the sense that we would need about 50k health before the EH gained catches up to stamina in item cost, and it is worthless against magic damage, which splashes all over the place in Ulduar. However, in a strictly physical fight in which one must choose between health and armor to increase EH, armor wins out every time.