Go to the Delvers and Denizens Index
My version of the fighter is essentially the same as that presented in B/X or BECMI. Though I have made a few minor changes.
I use a modified version of Weapon Mastery, which I've rolled into level training, so there is no longer a need to train for weapons separate from leveling up. Along with this, I've beefed up the fighters weapon training so that they get 1 new weapon mastery level at each level. though I have limited them to a skill cap based on level to stop them from just being grandmaster at early levels.
The other changes I've made are to the fighter combat options:
Cleave - available at 4th level this replaces the old 'smash' maneuver, lose initiative and must wield 2 handed weapon, apply -5 to hit in exchange for adding Strength score to damage, if kill foe then can attack another foe
Parry - the only change I made was to make this available at 4th level
Disarm - kept this at 9th level and just changed the save. Instead of making a DEX check, the victim of the disarm simply makes a Save vs Wands. so the fighter rolls to hit, the foe makes a saving throw vs wands adjusted by the DEX mod of the fighter(the save should already be adjusted by the victim's dex)
Multiple Attacks - made this available at 9th level, lets the fighter attack up to 2 opponents(and eventually 3 at 12th or maybe 15th level) at once, but not 2 attacks on the same opponent. I make this distinction to represent how I envision the abstraction of combat, the 2 sides are making multiple moves each round, and the to hit roll represents if any damage was caused from any of those multiple strikes; the attack roll doesn't represent a single sword swing, it represents whether a significant wound was caused.
Dual Wielding - available at 4th level, I've changed how this works a number of times, because I couldn't come up with something I was satisfied with while adhering to the design principles of Classic D&D. I wasn't quite happy with my most recent iteration, so decided to look The Riddle of Steel RPG, which gave me the inspiration to tweak it to something that I'm finally happy with.
So first the fighter must be weilding medium sized or shorter weapons; unarmed attacks with the fists or feet and shields can also be used as offhand weapons. Then the fighter must make a choice of how they want to use the offhand weapon. There are 3 basic maneuvers. 1) is the double attack where they simply attack with both weapons, this calls for separate attack rolls and damage rolls, but each roll to hit is done with Disadvantage. 2) is the Bind where the offhand weapon is used to control the weapon of the Foe. A normal attack roll is made with the offhand weapon, and if a hit is made any damage rolled is applied as a penalty to the Foe's AC for 1 round. 3) the last option is to use the offhand purely defensively to simply Deflect(or block if a shield) an incoming attack using the standard weapon mastery maneuver. 4) the fighter could use the weapon to perform a special maneuver if they have weapon mastery in the offhand weapon