Meaning of AC and HP - 1st attempt.

When people whom are not familiar with OSR games and Dungeons & Dragons' combat resolution system encounter it they may question the way it works. AC for a monster type doesn't always make sense – like a ghoul having AC6, or a Medusa AC8, and why doesn't wisdom add to the combat roll, given that being wise would help you to know when to strike. And dextrous charismatic swashbuckler types (not the level title) should get some form of attack bonus from high stats in those areas, no? Oh, and what's with those hit points anyway?

Saying that it's just game mechanics is fine. But I sat in the train and thought I'd like to BS it a bit better. This is what I came up with regarding the OSR games and B/X D&D versions – realizing that my stab at this is just as good/bad as anyone else's.

AC armor class.

AC is not only based on armor but a combination of armor worn as well as the general survival instinct helping you to dodge attacks. Therefore it is present even for unarmored characters where it is 9, and are modified by dexterity as well as armor.

AC can also be based on the creatures fierceness or a frightening special ability (like a petrifying gaze) making it harder to “go in” to land the hit.

This help explain the ghouls high AC. It's skin cant be that tough, but no one want to get close to those claws. And the medusa is served well by the attackers inability to look directly at it. And an ogres AC5? I'll take the skin could be as leather armor, but not chain mail. Those big crushing fists on an enraged stinking juggernaut might just make you hesitate a bit, though, adding the bonus of 2 or 3 to AC.

HP hit points.

Hit points symbolize the ability to withstand pain, resist strain, and perry at the last moment. Therefore constitution and class level affects HP. A fighter learn to dodge and perry better then a thief, and can resist more pain then a magic user. And someone with a high constitution can withstand shock better then someone with a low constitution. The attack and damage roll is therefore also modified by strength as strong attacks affect a person if it hits armor, and also course more strain upon the target if blocked or parried.

This works pretty well, and also make clear that it's not the ability to get a sword stabbed through the torso, and keep fighting. The explanation isn’t perfect, neither is the system. But I do think they boat work.

Weapon damage is based on weapon effectiveness and weight.

Given that they drain HP until the last moment this is the best I could come up with. It's more sensible with a wpn vs. wpn+AC with a set HP loss die per att, but then playability suffers. I might try to build it as an ivory tower pursuit some time though.