"However, the amount of damage 1 hit point represents is not on an absolute scale, but corresponds instead to the hit point total of the being hit."
The first 8-hp wound to a 10th level fighter has a different correspondance to his hit point total than does the last.
So, by "total" you meant "remaining"?
So the first attack is much less damaging than the Nth. That is exactly what the system was meant to do. [...] Both are 100% tangible. A nick and a sword through the guts are both 100% tangible.
My point was not that a nick was intangible. My point was that a sword blow that leaves a nick on a high-level fighter is doing negligible physical damage, equivalent to less than 1-hp damage on a first-level fighter. After all, he can take a dozen such hits before falling.
Since a high-level fighter's hit points are 90 percent intangible, we would expect attacks to do damage that was on average 90 percent intangible. (If the damage roll says 5 points, less than 1 point is physical damage.)
But we know that the
last attack is going to be more than 10 percent tangible, because it's going to involve a crippling injury, just as if it had struck a lower-level fighter -- so, to average things out, the first attack must be even less than 10 percent tangible.
The point isn't that the physical nick is somehow not a tangible injury. It's that the five points of damage clearly don't represent five points of physical damage, because that's enough to cripple a healthy man.
The healing rules in 1e do a good job, but not the best possible job, of defining how damage is healed. I would recommend house ruling 1 hp per day per level, so that that first nick is healed after a night's rest.
Of course, if that first nick were simply morale, it would go away instantly as soon as the fighter rallied.
I'm not sure we can say how quickly intangible factors should "heal" -- because it's not clear what that might mean.
If hit points are a measure of skill, we might look at doubling hit points as halving the amount of physical damage one takes per attack. So, it's not really that skill gets used up, just that the accounting is easier if we add hit dice, rather than do division with each damage roll. I don't think that linearity holds, but it would imply healing a constant proportion of hit points across levels. However long it takes a first-level fighter to heal one hit point, it would take an
Nth-level fighter to heal
N hit points.
If hit points represent luck or divine favor, who's to say how they operate? I can easily see luck points that don't "heal" at all, or that need to be re-earned through heroic feats.
If hit points are a measure of fighting spirit, then they should go up and down with morale, which can shift rapidly.
If hit points represent extra effort, they should return with rest.
And if they're some mix? Who knows?