Combat 

The following rules can be used to give more of the feel of sword and sorcery combat. 

Defence Bonus 

Characters get a defence bonus equal to their base attack bonus divided by 2 rounded down. This is added to your AC. 

Monsters get this bonus at the DM's discretion. In many cases a monster's natural armour bonus includes an element that comes from its fighting skill. In such cases the DM should not give a base defence bonus as well.

Why? This bonus is meant for use in worlds where magical armour is very rare. It simulates how difficult sword and sorcery heroes are to hit as described in the books. In addition D&D encounters tend to be designed on the assumption that characters will be of a certain AC at a certain level because they have acquired assorted magical protective devices. In most S&S campaigns characters will never possess magical armour and this bonus helps balance things.

Armour as DR 

Instead of giving a bonus to armour class, armour acts as DR/- equal to its armour bonus. Because a character can still be bruised, winded, concussed or stunned even through the thickest armour half of the damage stopped by the armour is treated as non-lethal damage. 

Shields do not give DR but add to armour class as normal. Magical armour should probably do the same with its bonus. 

The normal rules for stacking different types of DR as given in CR2 apply.

Monsters are treated slightly differently. Some of them have huge natural armour. Where a DM feels that this comes from a tough hide, metallic skin etc he should assign a DR as appropriate up to a maximum of 10. This should be subtracted from the monsters armour class as given in CR3. Really tough monsters are just too tough for most players weapons otherwise.

Why? Some people feel it is unrealistic that armour makes you harder to hit rather than stopping damage. This rule adds an extra calculation to combat and tends to make fights longer at higher levels but works very well with the Constitution as HP variant of these rules. You need to be careful with anything that makes DR very high because it can make characters all but invulnerable.

Quick Healing 

Since HP represent an abstract ability to absorb damage why not have them recover at level per hour UNLESS they go below zero in which case they recover in the normal way outlined in the PH. Using this system you don’t start recovering non-lethal damage until you have recovered all your HP damage.

Getting your breath back. Using this variant rule you can recover even quicker. As long as you have not lost more than half your HP, you are merely battered and winded. You can get recover HP and non-lethal damage at the rate of level per combat round of rest in which you do absolutely nothing. Once you have lost more than half your HP you recover at the rate of a level per hour, until you are over the half HP threshold.

Energy Drain and Negative Energy Levels 

In worlds where healing magic is rare or non-existent energy drains are far more threatening. In a S&S world they should never result in permanent level loss. A character should just repeat the saving throw to attempt to lose the negative level every day until it is made & the negative level is lost. To balance this the DM may only allow the character to make the saving throw to lose the level every week or month instead of every day. If your total number of negative levels equals your total number of levels you are dead.

Negative levels give you -1 per negative level to your spell fatigue roll.

Ability Drains 

Generally speaking the same thing applies to ability drains. They should be treated as ability damage instead. A good rule of thumb is; never inflict on a player something there is no cure from in the campaign. It does not mean finding a cure should be easy but there should at least be one available.

Finally it goes against the generally independent minded grain of the genre to have the heroes constantly running to uber-powerful NPCs for help. I think its better to let them heal most things on their own in their own time. These are worlds in which very often all a character has to rely on are his own abilities. It seems grossly unfair to permanently impair them.