The images provided in many of the game books regarding the appearance of Warforged gives the sense that they appear to be uniform to the point of being nearly identical. This state is similar to the clones in the animated series “The Clones Wars”. This is, however, a different circumstance because these are not living beings, but manufactured items, even if the manufacture might be done by artisans rather than in an assembly line. In a few cases it is mentioned that the nation of purchase would have their emblem marked upon their foreheads, but this is really underestimating the amount of both personalization that the Warforged would like to imprint upon themselves in addition to the clear markings for battlefield recognition.
Soldiers in the past wore uniforms to allow for easy identification during the confusing crash of battle. More modern armies, of course, still have uniforms, but the distinctiveness of uniforms has decreased as the need for concealment or utility has trumped rapid recognition. Even if they were simply tabards of one sort or another, each soldier should be expected to be distinctive from one nation to another. At the beginning of the Last War, this might have been impromptu, as the armies that the leaders of the Five Nations were drawing from were supposed to be part of a Galifar wide army. Indeed in the US Civil War, the South’s uniform wasn’t settled upon immediately, as the tension between recognizing the individuality of the States and their combined efforts played out.
How this would play out for Warforged would be that they would likely have been painted. If you stick to the cannon in the books, that suggested that the neutrality of the Dragonmarked Houses would allow for Warforged to be built in Cyre but used in Karrnath, than the painting would likely have been done upon delivery; having a unit of Karrnath painted Warforged marching through Cyre would not have been tolerated. This scenario, as I have previously discussed, is not logical to me; in a total war situation that the Last War is described as being, the various Dragonmarked Houses would be splintered along national lines, much like IBM’s subsidiary Dehomag in Nazi Germany. I believe that the Warforged would have been painted in house after their production by House Cannith, and that painting would reflect the nation of manufacture.
This can be used as part of a Warforged description, that they might maintain the paint that they were given, or it might have chipped and faded. That the Warforged were described, incorrectly in my opinion, as not having allegiance to their nation of manufacture once captured, their original paint might have been painted over, perhaps several times, resulting in thick layers that might weather differently. I suggest the use of paint rather than a cloth uniform as Warforged are rarely depicted wearing clothing and that their AC bonus is Armor not Natural Armor.
Another thing to consider is the end use of the Warforged. Having a look at the suggested starting ages, on average it takes 2.5 times as long to train a Cleric, Druid, Monk, or Wizard as compared to a Barbarian, Rogue, or Sorcerer (it’s only 1.6 times as long for Bards, Fighters, Paladins, or Rangers). That Sorcerers are often described as having something special in their blood that gives them their power, it is unlikely that a Warforged would become a Sorcerer. Similarly, unless as part of a special unit, good soldiers are orderly and disciplined, so training a Warforged to be a Barbarian would be unusual. Finally with the question as to the nature of a Warforged soul (they can be resurrected but they can’t become undead), there would likely be few Warforged Paladins. I am unable to find any details of the length of time to become an Artificer, but I suspect it would be in line with being a Wizard, so while there is great synergy for a Warforged to become an Artificer, it would be similarly rare. This does not mean that players can’t choose to become one of these classes or for a DM to make one, but that from a manufacturing perspective, it is easier to make a Warforged Fighter than it is a Warforged Wizard.
This implies that the vast majority of Warforged would be Rogues, Bards, Fighters, and Rangers, if the length of training is used a deciding factor; I personally disagree with the idea of NPC classes, so I am not including them in this discussion. Rogues and Rangers would act as scouts and skirmishers, Fighters would make up the bulk of the forces, with Bards alongside as buglers (or similar military musical instruments like “drums, fifes, bugles, trumpets or other horns, bagpipes, triangles, cymbals” – Wikipedia), signalling orders.
The ability to be heard over longer distances is increased by lower tones, and it would be beneficial for a soldier to be able to shout a warning that would be more easily heard than not, so most Warforged would likely be bass in tone. It would be an impressive sound to hear a unit of Warforged doing a battle cry, or to hear them singing a marching song, something that could be instill fear far in advance of their appearance, or to see them do a haka on the battlefield.
To reduce the ability of the enemy to determine their numbers, Warforged would likely have similar treads on their feet, and would be trained to step into the footprint of the soldier ahead of them while on the march. This could make tracking of a Warforged difficult as it would be hard to distinguish one Warforged’s footprint from another. This could be further improved if they wore boots.
While they would have to stay within the Medium size so as to have easy access to Medium sized weapons, Warforged would likely be very tall. A typical door can let pass a 6’ 6” person without having them duck, so I would suggest that a typical Warforged would be about that height. I say this because height is a useful factor in intimidation; border guards at contentious area are often selected for their height and may even wear shoes that boost them by an inch. On the other hand, Warforged that are Rogues or Rangers might be on the low side of the Medium size, but not below the average human size, so as to better appear to be regular humans if viewed from a distance, around 5’ 7” (the average of both male and female humans).