Armor as Damage Reduction 

I like the concept of armor wearing out during a fight, but keeping track of things was a pain. Now if a monster deals a critical hit, before damage is rolled I offer the players the option to take normal damage by sacrificing their armor/shield/weapon. If they have a lot of hp they choose to take the hit, if low on hp it becomes more of a gamble. It becomes even more painful when the armor/shield/weapon is a prized magic item.

Based on the Backswords & Bucklers game and my HEMA experience, I go with armor doing Damage Reduction. Defense is calculated thusly: 10 + Dex Mod + Base Attack Bonus + 2 Shield (or + 1 for second weapon)

Ascending and descrnding AC is the same math but turned around. Your THAC0 improves with level, heavy armour makes you harder to hit. You turn the same formula slightly on the side.

Also, historians has recently discovered that soldiers and knights learned to use their swords if ver different ways than what we see in the movies (I.e. just held by the handle and striking with the blade). Illustrations show swords held by the blade (with gauntleted hands) and using the crossguard as a military pick, or one hand half way down the blade to guide it to a weak point on their foe (visor slit, gap in a shoulder plate, etc). This could be assumed as PC roll their attack as they would use their weapon to maximum efficiency, especially warriors classes.

Most medieval knight’s shields 🛡️ were not steel, but composites of wood, leather and gesso. The edges may have been reinforced with steel on the edges only. Otherwise it would be too heavy. In the Renaissance steel rondel (small round shields about 12 to 18” diameter) and steel bucklers (9 to 12”) were popular with the Spanish Tercios.

2e had three damage types for weapons. Piercing, slashing, bashing. A plate suit could have high AC to slashing but AC closer to soft armour for bashing. So a pick that made less damage would essentially have a greater chance to hit plate.

The thing about adding damage reduction to a system or replacing armor class with is the complexity tax it introduces. Yes, armor reducing damage is more realistic. Reducing specific types of damage more than others is more realistic. But it becomes harder to manage. AC is a flat +5% difficulty to hit you on a d20 roll. Reduction will change the proportion of damage it blocks based on whether your being hit by one big attack or several smaller ones. And as enemies scale up, their damage has to also increase proportional to your improving damage resist. Which means fighting something noticeably more or less powerful will result in your defenses being disproportionally terrible or practically invulnerable. The AC system means everything is affected equally proportionally.

My HEMA friends describe shields as a partying tool. MERP shields work a lot like that. I like the simplicity of simply granting +1 or +2 to your combined AC. Police in Esoteric Enterprises often have more armour than your criminal PCs but they are always one encumbrance level higher. You can outrun the SWAT team.

I was introduced to ruleplaying in a damage reduction system. You could add a bypass system where armor has 2 values, coverage as the present AC and armor value as the damage reduction. Pair it with ac to touch and you have a threshold zone where armor works but go beyond that, full damage.

Just found you guys and like your back n forth ideas and explanations

I don't know why YT bring up this video but I started to think about this topic in the last few days. I originally played a system other than D&D. It considered a D&D clone but it used a damage reduction system where the heavy weapon reduced more damage but it also reduced your Dexterity and Agility. There are 2 things what I didn't like about it. First the book tried to explain that the armour reduced the damage because you couldn't penetrate it that much. While that make sense for lighter weapon, it doesn't really work for plate. Because even weapon what can sunder an armour are can't really get through it. A war hammer wasn't good because it went through armour it was good because plate armour wasn't really good stopping blunt force (plus it damaged the armour and made less comfortable to wear it in a battlefield. My second problem is what I like to call a the "dagger problem". In Damage Reduction system a dagger do nothing against an opponent who wears a plate armour but in IRL a dagger (especially something like the Rondel) was really good against armoured opponents. Not long ago I started DM a team where almost everyone is a newbie and at one point they got to blacksmith and they asked me if there anyway to upgrade their weapons. I told them there aren't rules for that in the base game but eventually I probably can come up with some ideas. Not much latter I came to conclusion that for that I need to change some weapons in the game. Foe example I plan to introduce some new weapon properties. One of them would be 'sundering'. I'm not sure yet how I will implement. Maybe it should be a different action or maybe it would activate if your weapon miss by one. I don't know if it will work but at least this would simulate the armour damaging properties of certain weapons (thou it wouldn't simulate how certain weapons would work against certain armour types better).

Look into the age system for this as well. It is a damage reduction armor 3d6 system. You can increase the damage of the attack through stunts gained through doubles rolled on attack or through use of armor bypass mechanics with piercing or penitrating attacks.

like the conversation:) thanks for sharing

Cyberpunk 2020 had social limits to armour. The don't let a madman in MetalGear into the pub. Anyone in MetalGear on the street shouts "company hit team" or "SWAT". You can do it but no one who sees you will be surprised. Armour better than ballistic tees make you slower and lowers initiative, but armour often saves people from lethal damage.

For my homebrew AC applies but heavy armor has damage reduction as well

It’s true that some weapons are better against some types of armor, but adding modifiers to reflect this in game may not be for everyone. This would going back to the old AD&D THAC0 system. Besides, would you also apply modifiers to monsters that don’t use melee or ranged weapons and what about those monsters and their AC, are their bodies protected by hard scales or skin (dragons), thick hide and fur (bears), resilient “blubber” (walrus or purple worm). All things that would need to be considered and worked out ahead of time…and then everyone needs to remember to use these rulings.

i am starting to playtest my own ttrpg now and in my mechanics i remove hitpoints and play with hits. so the armor will just absorb said hits until its broken. having to use part of your action economy for the blocking sounds interesting. might try to incorporate that

first ed was NOT THAC0 -- it was purely tabular .. very much based on Chainmail.

I use AC as DR - makes sense - the idea wearing full plate "harder to hit" is nonsense - if any person throws on 50+ pounds of plate, I promise you they don't dodge or move about as swiftly, and thus easier to hit them... just the hit doesn't do as much. I'm making my own system, based mostly on Pathfinder 1e, and these are the basics of how you can apply it to a standard PF1e game or similar: -the "AC" is now "DEFENSE", and amor grants DR/armor equal to what the normal AC bonus would have been -every character applies their base Reflex save bonus from class to their DEFENSE score - so with "training/experience" they learn to avoid being hit -Called Shot (per Ultimate Combat) rules can allow a character to ignore or bypass some (usually half) of the DR from armor... for example, foe wearing full plate - call shot to eyes, joints, areas of armor that are exposed -"Dismantle" as a Combat Maneuver - on a success, you can temporarily reduce the armor's effectiveness by 1 (or 3 if succeed by 10 or more) - thus armor granting DR 8/fullplate could be reduced to 7 with a successful CMB check to Dismantle it a bit - takes 5 minutes of work to readjust armor to fix (basically warping armor pieces, cutting straps, etc) Hope this gives you all some ideas

Is that a skull bong?