Ok, I think we're talking past each other. Let me recap.
What I want is a Henry V style character. He can belt out the monologues and convince people to do stuff, and he can mix it up with the best of them. So, with that in mind:
What I want
Full, or at least close to full attack bonus
Heavy armor
Full diplomacy ranks or at least close to full.
What I don't want
Spells
Magical abilities
Alignment restrictions
Abilities that a nobleman would not likely have.
Now, from what I've seen, my choices are:
- the Cosmopolotin feat (non-core - Eberron Campaign Guide IIRC, so, 3.5),
- Greg K's don't play 3e, just make up your own rules option,
- Burning a feat and going cross class (the only actual option out of core)
Again, I'm not talking about a unique snowflake here. Commander Carrot from Pratchett fits this bill pretty well. Any non-magical Knights of the Round Table sort also fits. Whatsisface, Maximus from Gladiator fits this bill. Heck, the guy from 300, I'm so bad with names, also works here.
It's a pretty common archetype, yet, for all the vaunted options of 3e, I've actually got surprisingly few choices for making what I want. And, most of those choices aren't a very good fit either.
You think you need mechanical max diplomacy to play those guys? Not just roleplaying a speachy leader? Charisma alone is insufficient mechanically cover the concept with a stat? I think Roy from OotS fits this archetype as well and does fine without apparently maxing his diplomacy.
Fighter with maxed core class intimidate might work for some of these badass warrior leader concepts. However if you mechanically want to nonmagically change NPC's attitudes in 3e then it is indeed the diplomacy skill you want.
So you have your 3 presented options
1 RAW fighter with feats and maxing cross-class
2 Cosmopolitan feat from a splat
3 Tweaking classes as suggested in the rules
Core you could also go with the npc aristocrat class who gets the armor and weapons, 3/4 BAB and class diplomacy skill. This could be taken straight or multiclassed with fighter for the concept. This has the drawback of being a little weaker combat balance wise as an NPC class.
You also have the rogue for nonmagical multiclassing, which will work with some of those concepts (300 group fighting and surprise devastating attacks seem to fit sneak attack). This has some class features you might not want (trapfinding, etc.)
You also didn't have to wait until 3.5 for cosmopolitan though, the Forgotten Realms Campaign Setting came out pretty early in 3.0 and has the feat in there. As well as education which makes all knowledge skills a class skill.
And then there is the PHII knight, who I expect has diplomacy, though I don't have it in front of me to check.
Unearthed Arcana presented a variant rogue who got fighter bonus feats instead of sneak attack if you feel the SA is objectionable.
As noted you have the Complete Warrior swashbuckler which gives 1/1 BAB, no spells, class skill diplomacy, but they do go for a light armor concept.
I forget if the samurai has diplomacy, though he has the japanese flavor and two weapon fighting style.
I've only seen marshalls second hand so I don't know if their inspiring aura powers are clearly supernatural as written or 4e warlord style inspiring with flexible fluff.
However I do agree that the class RAW skill/cross class skill and few skill points set up of 3e is an obstacle to branching out of the D&D archetypes.
In archetype 3e every core class except fighter, barbarian, and wizard can max out diplomacy. If you want to be a nonmagical big weapon heavy armor warrior with good mechanical diplomacy you have to put in effort to work the system.
I much prefer making all skills class skills or going with the pathfinder skill system where cross class is not crippling in point expenditure.
* I see I was scooped on the aristocrat idea. Ce la vie.