Alright cool, back to me.
Weapons in general do 1d6 damage. This is enough to kill a guy if he gets hit wrong. To cushion the blow a little bit, I like to have zero hit points be "incapacitated but probably dying," the better to let the players drag each other to safety and have fighting be dangerous but less so. (Death occurs when your hit points are at your negative constitution score- so if you have 10 CON you'd die at -10. If you're incapped you "bleed" a hit point every round until you're finally dead.)
Fighters get +1 to their attack every level. If you're using THAC0, that lowers by one every level. They get +1 to their Armor Class every other level (so levels 1,3,5,7,9) as long as they're "ready." This basically means that they don't get their AC bonus if they're being ambushed or sucker punched- this bonus AC is from them being able to dodge, parry, and roll with the punches.
Non-fighters don't get anything special. Sorry guys. Everybody does still get their normal saving throws. I prefer the ones from Sword and Wizardry ( a single "saving throw" that gets better with levels) but I don't know if it really makes a difference which ones you use.
Magic users still cast spells, and at the same rate. They can use whatever weapon they want, because they're not going to be very good at it anyways.
Same with Clerics. Specific clerics might have specific strictures (no sharp weapons being a common one for clerics of a peaceful religion), but they otherwise can wear any armor and use any weapon. No attack bonus here, so clerics are less frontline fighter and more armored wizard.
Thieves, if you choose to include them, are relatively unchanged, except for the lack of attack scaling. You can give them a +1 at first level if you like, to let them do something, but considering that their main use is out-of-combat anyways (and that they tend to ambush more than fight fair anyways) you probably won't notice anything.
This variant means that the focus is off the infamous "You hit the orc for 4. The orc hits you for 3. You hit the orc for 2. It dies." that inflated hit point combat kind of feels like. It does mean that fighting men have a more limited lifespan at higher levels but you know, honestly, I can deal with that. Punching dragons in the snoot is generally a bad idea; at the very least you should take your magic sword and stab them in the eyeball or something, and that's the sort of thing that is simulated in the fiction extremely badly by combat rules. You don't "fight" a twenty foot long serpent, you encounter it and are going to need to figure out how you're going to stop it.
|I move five feet towards it and attack with my axe.|
It's a smallish tweak that I'd play in a heartbeat.