There has been some talk in the past about how armor class isn’t very realistic. In a more realistic system, armor would reduce incoming damage by absorbing some of the impact. Rolling to hit is better adapted for foiling dodges and parries to actually land a blow, while armor should be applied to the damage itself.
That all sounds plausible, but it has the drawback of adding extra steps to combat encounters. In addition, the armor class system – i.e. rolling high on attack attempts to damage an opponent – is actually an excellent abstraction of what it’s like to fight against an armored combatant.
Finding the Gap
These ideas come from one of Matt Easton’s videos, namely this one (mostly the second half, but it’s all informative). In this video, he looks at various period artworks and discusses where you’d target attacks when when fighting individuals in armor. The point is you’d target unarmored areas, and most armored individuals have at least a few gaps in their armor.
The better the armor, the fewer and smaller the gaps or the hardier the material. Now, I don’t know about you, but to me that sounds an awful lot to me like how armor class works. If you roll high, you found a gap (if fighting against plate or mail/brigandine) or breached the material (in the case of textile armors or mail).
If you do not overcome a target’s armor class, you hit the armor and your attack wasn’t substantial enough to compromise the material. Or you just missed, either due to parries or dodges.
Clean, simple, and it’s actually fairly realistic.
It Depends, Of Course
Naturally, this all depends on how we define “damage” and “hit points” in our game. If hit points are purely “meat points,” then the abstraction represented by armor class is more or less perfect. Every bit of damage represents a measurable injury resulting from defeating or circumventing the armor. Anything that wouldn’t constitute a meaningful injury – such as fatigue, minor bruising, or mild discomfort – is simply considered to have been stopped by armor, deflected by parries, etc.
On the other hand, if hit points are not meat points, then armor class carries a bit of narrative dissonance, and a different system would likely represent armor’s role in combat more realistically. Sure, you can still narrate attacks being mostly stopped by the armor, but what if the person getting hit isn’t wearing armor? I suppose it can be argued that the loss of HP simply represents the additional strain of having to avoid more hits rather than relying on armor, so maybe it balances out that way. However, that’s supposed to already be represented by the Dexterity bonus to AC, so it seems a bit redundant.
We’d also have to stop narrating HP loss as “hits” and call it something else. It’s a little confusing to tell people that they avoided damage by taking damage to their HP. However, that’s more a problem with hit points rather than armor class.
Possible Adjustments
There are some ways we can adjust this system to add realism, of course. Here are a few I’d recommend.
Make Hit Points Equal Meat Points
Lowering hit points and making sure they represent muscle, bone, and sinew can solidify this interpretation of armor class, which is something that is done in many OSR style games as well as ICRPG.
Shock Damage
One can still be hurt through their armor, and a person who is wearing armor may still be spared many of the more serious injuries that an unarmored person would sustain, even if someone finds a gap. Mail voiders, for instance, protect certain areas enough to turn an incapacitating wound into a mild hurt. In addition, highly percussive weapons can still batter a person while still technically hitting armor. How do we represent that?
A method I’ve mentioned before is the shock damage system from Worlds Without Number. I might simplify it, of course. If an attack roll with these types of weapons beats a 10, it does a little bit of shock damage (1 to 3, usually). If you want to get more granular, add Dexterity to that target number, but that will constitute more calculations for you and your players to make at the table.
Change Damage Against Unarmored Foes
A truly simple system would just be to roll double damage against unarmored opponents. A sword blow through a mail voider would likely do far less damage than it would through a completely unprotected armpit. Clean, simple, and no extra math steps for most situations. It’s also narratively consistent with critical hits doing double damage as well – you hit a vital, unprotected area.
Just Don’t Change It
Alternatively, just leave it as is. Armor class is a perfectly fine system on its own.
Ditching Armor Class Anyway
Of course, if you want to use something other than AC at your table, damage reduction is still viable. Speaking as someone who has run a game using armor as damage reduction for a while, I will warn you that this will make your game more focused on combat since damage calculations will take more time. If you want to expedite combat, try removing stat bonuses to damage. It’s a lot simpler – at least for me – to roll a die and subtract armor in my head than to roll the die, add a stat, then subtract a different number from that total.
If you want to an example of how damage reduction might be applied in a 5E game, check out Halls of Ringing Steel on DriveThruRPG (it’s free!). The main change I’d make to that, however, is to make armor values lower (maybe by 2 points) to keep combat dangerous.
Alternatively, you might use armor as hit points. Better armor gives more HP. This plays well into the concept of HP as “hit protection” that we see in Into the Odd and Cairn, so I’d recommend that if you want to keep things simple. You can even eliminate attack rolls!
In either case, do what you feel will be most fun for your table. After all, isn’t fun why we’re all here in the first place?
The Astral Wanderer is brought to you by the clash of ringing steel and cries of pain exuberance at winning hard-fought victories. Support this blog by sharing it with other gamers or by buying my stuff! All proceeds go toward finding ways to pierce mail voiders with pointy swords. Really.