Fighter: Student of Many Styles

It's a fighter that develops in random directions, steered by the player.
This is not polished, it is minimum viable product. Only the barest thoughts have been given to balance. This might be overtuned. On the other hand, fighters should be good at fighting.
I think that you could take Parry, good with shields, the parry-improving technique, and wear heavy armour and you'll be REALLY hard to kill. I'm not sure how I feel about that.

Or if you got extra reach, cleave, and finished with Kill The Mooks you'd be able to mow down weaklings like anything.

I can see some anti-synergies between some things: if you punish misses by attacking more, and attach a maneuver to each of your attacks, so the enemy tries to hit you and misses EVEN MORE,for more attacks... then is it good or bad for you to improve your maneuver so that it doesn't provoke enemy attacks? Same thing with a crit build vs Kill The Mooks.

I also note that it's quite possible to create a fighter that only ever gets one attack per round. That sorta feels wrong. But maybe that's OK.

 In short: if something in this feels wrong for you, it probably is wrong, and should be adjusted.

Chassis

A: 2 Fundamentals, 1 Technique, Attack +1
B: 1 Technique, Attack +1, Extra skill
C: 1 Fundamental, 1 Technique, Students
D: 1 Secret Art, 1 Swappable Technique

You begin with an interesting scar, two weapons OR a weapon and shield, medium armour, and a tome of esoteric fighting techniques.
You are proficient with all normal weapons and armour.
Starting Skill: 1. Mercenary 2. Foreign Parts 3. Monsters

Fundamentals

Each time you get a Fundamental, pick an item on this list.

• Weapon Notches: Weapons get better at 3, 10, 30, and 100 kills. You can take the same thing more than once.
  
• +1 attack
• +1 damage
• Extra thing
• Keen edge
• Parry: Or you can call it Stance. You have [2, 3, 4, 5] hp of overshields each round.
• Tactic master: When you hit an enemy, you can also make a maneuver against them (does not remove the normal chance of being hit)
  
• Cleave: When you kill an enemy or crit, you can make an extra attack.
• Good with Shields: Extra +1 Armour from shields, can always sunder for maximum
• The Good Power Attack: When you power attack, the penalty is only -2 rather than -4.
  

Technique

Each time you get a new Technique, roll TWICE on the list, and pick ONE to gain. If you get an entry you already have, reroll that one. I kinda want to be able to increase this chart to a D66, so I need 3 more ideas.

1. Head of John: Your head becomes indestructible. It's a good weapon.
2. Pattram Sword Hand: Your unarmed strikes are just like swords. Work out the specifics.
3. Horse Stance: You no longer get tired from walking or running any distance as long as you are not overencumbered.
4. Chan Style: No item you use as a weapon does less than 1d8 hp and you don't take penalties just for trying to use it (though it may only be good for one use if fragile). If you have a strength penalty to attack/damage, that's also ignored.
5. Swat Missiles: You can smack incoming missiles out of the air if you make a successful attack roll.
6. Protecc but also Attacc: If an ally is attacked by an enemy, both within your reach, you may make an attack against that enemy first.
7. First strike: When an enemy moves within your reach, you may make an attack against them immediately.
8. Infinite Tumble: Move past enemies or disengage without provoking attacks
9. Discliple of Guts: You learn how to carry and effectively use ridiculously oversized weaponry.
10. Punish Incompetence: When an enemy misses you, you may make an attack against them.
11. Keen. Your critical range expands by one.
12. Spellsword: Roll a random spell and gain one MD. You're good with spells now.
13. Bloodlust: Gain HP when you kill an enemy, equal to how many HD they had. No "angry turtles in a bag" strategy, please.
14. Ignore Injury: Mere pain, shock, bruising, bleeding, cold, burns and the like no longer hampers your ability to act - only extensive damage like shattered bones or loss of limb.
15. Follow Through: When you kill a creature, damage exceeding their remaining hitpoints gets applied to other targets you could also conceivably attack with the same action.
16. Size up: Can tell most important enemy stats at a glance: hitpoints, armour, and their strategy.
17. Air Blade: Can make ranged attacks with melee weapons.
18. Implacable: You are immune to fear and get a +4 to saves against other mental effects. Allies near you get a +4 to saves against fear.
19. Extreme Parry: Double your parry.
20. Dash Master: Get a 10' Dash as the Skirmisher (that is, a 10' horizontal dash, 1/round, usable at any time including when an enemy is about to attack you)
    
21. Extra Quickdraw Slots: You get another 3, like a Thief
22. Lightfoot: Your footsteps are so light you can tread on water or snow without falling. +2 stealth.
23. Elemental Affinity: Pick an element. You can use it to perform 1d6 attacks and achieve other small-scale effects.
    
24. Elemental Resistance: Pick an element. You gain resistance to that element equal to your HD.
25. Danger Sense: You cannot be surprised.
    
26. Situational Extra Attack: Come up with some particular circumstance that gives you an extra attack.
    
27. Effective medicine: Gain the Medicine skill. Rolls to prevent someone dying from their injuries succeed on a 3 in 6.
28. Equipment trick: You can make better use of a kind of equipment, especially in combat. E.g. drinking things like potions can be done for free. Or you're good at using ropes are weapons.
29. Zoom Punch: Space seems to warp around you, your reach is much longer than usual.
    
30. Petition DM: Ask for a certain item on the list, or a feature you can find from another class, or something custom, of appropriate power. Try improving a technique you already have, or some set of circumstances that gives you an extra attack?

Other ideas: Extra HP. Reduce impact of Death Dice (make them d4s). Not being able to see doesn't negatively affect your ability to fight.

Attack +1

This is a +1 to your ATTACK ROLLS, not an extra attack.

Extra Skill

Gain an appropriate skill.
[To do: suggest some skills]

Students

A travelling student finds you, wishing to learn from your example. Treat them as a level 1 Student of Many Styles. After a week of learning from you, treat them as a level 2 Student of Many Styles; the technique they gain must be one you have. After a month, they will move on (and are soon replaced by a new student) unless they are furnished with a good reason to stay.
They are willing to EITHER pay you, work for you, or fight for you in exchange for teaching.

Swappable Technique

Pick a technique on the list, gain it immediately. You find this technique difficult; it runs against your deeply ingrained habits, and requires regular practice/meditation for it to remain usable.
You may swap this technique out for another in a week of downtime.

Secret Art

You gain one secret art: some ability of significant power, known to very few.  You might be the only living practicioner. You get a secret art that is most appropriate for your character - according to your needs or historical approach to solving problems. You and your DM can work out the specifics. Some examples are given.

• Ability to cut things that should not be cuttable, such as very hard materials, or space, or truth (pick ONE)
• Perfect Tactical Foresight: declare that the combat round that just happened was only "what you saw might happen". Everything gets put back as it was a round ago and we get a do-over. Nobody will be able to remember the exact hitpoint totals that anything had - close enough is good enough.
• Hadouken. A big one.
• Za Warudo. Two full rounds of action. Once a day.
• Kill the Mooks. Attacks against nameless mooks (2HD or less that the DM hasn't named) always hit and always kill.