Armor Class without Shields

One of my favorite renditions of Swords & Wizardry is Mike Davison's Ruins & Ronin. One of the minor tweaks that I enjoy is the way R&R handles armor and AC. Since the Japanese historically did not make use of the shield in the same way the Europeans did, shields are not part of the game, nor are they there to create a nice, clean AC progression. Rather, R&R allows players to cobble together various armor pieces where a full set of O-yori armor is AC -1.

If this principle were applied to European armor, then several aesthetic and mechanical things could be accomplished:

• It allows players to be more whimsical in their character conception through armor
• It has more potential for respresenting historic armor types from a wider range of time and place.
• It allows the shield to be something other than an AC modifier
• It conceptually makes more sense with a Weapon vs. AC table than the traditional "+shield" AC progression.
• It suggests a simple encumbrance rule where AC (modified by STR or DEX) x10 = movement (I must admit, I am borrowing this from something I read in the blogosphere, but I cannot remember who was the originator).
• It can make helmets mechanically important.

At the moment, I am approaching this from an abstract pov, so as to make it as flexible as possible. If the body is divided into three parts (head, torso, lower body) and armor divided into three types (light, medium, heavy) this creates the potential for an AC progression of 9 (no armor) to 0 (heavy armor for all three body parts) where Heavy = -3, Medium = -2 and Light = -1.

In addition, the torso and lower body can be divided into parts. Each part can have different styles of armor. Add up the different parts, divide by the number of parts (rounding down) in order to get the AC. For example, a retiarius gladiator is often depicted wearing heavy armor on one arm, but none on either the chest or other arm. Thus -3 +0 +0 = 3; 3/3 = 1. In addition, they are often depicted with a heavy armor helm. Thus, the final AC would be 5.

Movement rate = ACx10. This can be modified by the STR bonus. Thus, AC 0 with a 13 STR would allow a movement of 10 ft. If the character is wearing nothing but light armor, the STR bonus can be substituted for the DEX bonus.

I must admit that I am thinking of using this set-up in context of the 1 hit = 1 hp experiment I came up with over the weekend. Therefore, the following are directly related to that concept; however, with a little fiddling I can see them applicable to a variable damage system as well.

• Shields can negate one attack per round; however, the character using the shield cannot attack the creature whose attack was blocked that round.
• Two-handed weapons do +1 damage (x1.5 in variable?)
• Wielding two weapons affords a +1 to hit (allow the character to add their DEX bonus to hit?)

I would also consider making the latter two only available to fighters.