OK, think I've pretty much got a workable system sorted.
I started with the gentlemanly - and not so gentlemanly - art of fisticuffs and worked out what sort of damage the average joe should be able to inflict upon another average joe - strength and body bonuses irrelevant.
Based on my own observation of the average punch-up, an average person is not going to do a lot of damage with fists alone. Bruising, winding, black eyes, blood noses, split lips, loosened teeth, stun. Unlikely to break bones but can do a reasonable amount of damage if critical areas are hit - groin, solar plexus, kidneys.
Add to this the fact that the average person cannot hit worth a damn - they may occasionally fluke it, but they have no idea how to effectively channel their body's full power into the punch. Trained/experienced fighters, boxers and martial artists can, but the average citizen - even the strong ones - does not use their full hitting capacity.
In a typical "scrap", expect soreness, swelling, bruising - "flesh wound" sort of stuff and both parties departing a little tattered but not seriously wounded.
Occassionally, a serious wound might be inflicted, teeth might be lost, a person might sustain serious damage to internal organs, easy to break/dislocate bones (nose, jaw) may be broken, person may be KO'ed.
Going by FNFF2013, for an average person a flesh wound is 1-4 points, a serious wound is 5-8 points. The average person should not be able to inflict anything more than 8 points of damage anywhere on the body - including the head, which takes double damage.
This puts the damage dealt by the average human fist around 1D4 before any modifiers.
Someone who knows what they are doing would be able to inflict more damage, as would someone stronger.
Still trying to work out whether a kick should be 1D6 or 1D8 - haven't done all the sums for that, yet, but a kick is definitely more powerful than a punch.
Modifiers:
Well, there's the strength ones, obviously. Peewee is going to hit like a wet noodle at -2 (minimum 1), Ahnuld is going to do +2 as per the standard cyberpunk body type strength modifiers.
What if they do know what they're doing?
And here's where I branch off totally from Cyberpunk's take on martial arts.
As stated above, the average person does not know how to punch or kick properly, they use less than their body's full striking potential.
Once a person learns how to strike properly, they can use that body's full potential. But that's it. Nothing more. Martial Arts, contrary to what the movies and CP2020 might tell us, do not turn you into a killing machine capable of punching a 200-lb opponent the length of a basketball court. What they do is teach you how to set your body so that you use all your strength to hit - with no weaknesses on your part to rob the strike of its sting.
You typically learn that long before you get to blackbelt.
So, my take is this:
In boxing, brawling or any martial art that uses strikes:
Trainee +1 to damage
Adept and above +2 to damage
Martial arts that use kicks get the same bonuses to kicks. Perhaps even +2/+3, given that they teach movement dynamics to accelerate a foot far better than you can accelerate a hand.
But that's it, that's the extent of the damage bonuses for martial arts, boxing etc. You learn to use your body's strength to its fullest extent at Adept (or around level 2 in the art if you use the standard cyberpunk skill resolution) and anything above that just increases your chances of actually hitting your opponent or blocking his/her attacks.
So, Joe Average who's adept at boxing is going to do 1D4+2 with his fists.
Except:
The naked hand or foot is not an ideal thing to hit with. I came up with four classes of cover: Naked, soft, hard and heavy.
Naked would also include negligible cover such as light gloves or socks. I've put a -1 to damage on this on the grounds that most people (not high on drugs or so far lost in rage (or so drunk) that they don't care any more) are going to instinctively pull their punch/kick a trifle to protect their bare hands/feet. That also makes it slightly less likely for an average punch to the head to do serious damage. May not apply under all circumstances.
Soft - casual shoes/sneakers, padded leather or Cordura motorcycle gloves: no modifier. The person hits to the best of their ability.
Hard - hard leather shoes or boots, motorcycle gloves with plastic or carbon fibre over the knuckles: +1 to damage.
Heavy - Steel-capped boots, brass knuckles: +2 to damage.
So, a very strong and adept boxer with a knuckleduster is going to wind up doing 1D4+6 damage with a straight punch - if that connects with the head, the average recipient is going to be in serious trouble.
However, a punch-up between a couple of average guys in a pub is probably not going to result in a trip to the hospital unless one of them smacks into the edge of the bar as he goes down...
Still need to do the maths to work out what damage the average kick should do and whether the training mods should be +1/+2 or +2/+3 but I feel confident that I've got the fist-fight figures somewhere between 2013's "divide everything by 5" soak-up-an-infinite-number-of-punches and 2020's "why have a pistol when you can head-kick them to death?" that does close to real-world damage levels. Supplementary injuries are of course modified in keeping with "non-penetrating" wounds: broken bones, pulped squishy bits, lost teeth, black eyes, detached retina, temporary or permanent brain damage etc...
I saw an alternative damage table that assigned 1.5x damage to abdomen injuries and I'm inclined to agree with that system. Also think that damage to groin or kidneys should have around a -2 to your stun number. Fail and you're on the floor deciding whether or not to vomit...
So, with double damage to heads and damage-and-a-half to guts and groin, the average Joe with no modifiers at all should be doing 2-8 points to the head, 1-6 to the guts and 1-4 everywhere else. Against the average opponent, that's enough to seriously wound heads and squishy bits but not enough to do much to arms, legs and chest - which is pretty much right for the average punch-up between guys bickering in the pub. Things get a tad messier when Jake the Muss steps in - strong and adept and just as likely to use a bar stool as his fist...
When looking at the damage feet in steel-capped work boots can do to heads - even at 1D6 damage - we're getting into mortal wound and death territory, which is reasonable to expect. I'm not thinking Chuck Norris head-kicking everything to death to the point that the audience falls asleep, I'm thinking punk "laying the boot in" against a downed opponent... which I've been told constitutes "assault with a deadly weapon" in Texas.
Seriously thinking of giving modifiers to certain types of strike - e.g. negatives to haymakers as they are mechanically inefficient; positives to back-handers as, when properly applied, they use the body very efficiently.
I also came up with some preliminary figures for how much damage the armour soaks up - Type I and II halve the damage and convert it to bludgeon, Type III-A and up divide the damage by 3 and convert to bludgeon.
Even with those figures and figuring 1.5x damage for a gut shot, a powerful weapon at point blank is capable of major, potentially life-threatening, damage to internal organs even if completely stopped by the armour.
Given that under CP2020 you subtract SP and BTM from the damage a bullet does, down to a minimum of 1, I think my system's a tad nastier. A 9mm at point blank may well be stopped by Type II armour but half of its 2D6+5 damage is going to get through as blunt trauma. You may be lucky and escape with bruising to the chest - or you may take a serious thump to the stomach, winding you, forcing you to save vs stun for serious wound etc.
That same 9mm pistol is not going to be as effective against the Type III-A armour worn by the cops, of course, but a .44 Magnum is a force to be reckoned with.
Of course, that was the "stick the pistol in his ribs and pull the trigger" value, damage drops off over distance.
Also still working on realistic figures for damage done by various melee weapons - even an average punk with a beer bottle can do serious damage as recent news reports over here can attest.
Also got to get my kids running backwards and forwards across the park to start working out suitable negative modifiers for called shots. Don't worry, I'm not actually going to shoot at them, just see how big their torsos and heads look at various distances.