Beneath Aetherian Skies
Warforged: Artificial Life
The warforged (both singular and plural) are an oddity in the sense that they are fully sentient constructs. They are given life by binding an elemental spirit to the humanoid chassis as its power source; the ancient rituals used in constructing these beings somehow synthesize the elemental spirit into something completely different, effectively melding it with its body and creating an all-new conscience: that of the warforged. The secrets of this process have long been lost to the ages.
Although arcanotechnology is known to have originated in Dominus, the only force known to employ more than several (reportedly, an entire legion in fact) warforged is House Ravenstein of Padavona. Whether they have been unearthing these living relics from within Tieresia or bringing them in from off-continent, none can say.
The warforged appear, for all intents and purposes, to be living suits of armor. A quirk of their internal systems allows them to assimilate armor that other races would normally wear: A warforged rogue donning leather armor somehow 'consumes' its armor and the leather straps manifest on its body (a warforged fighter in full plate is appropriately more menacing). The warforged themselves claim that they are built to be variable weapons platforms, capable of integrating their weaponry and armor into their own frames. They speak in an echoing monotone that occasionally attempts to emulate emotion, theorized to be a trace of their souls' origins.
Warforged mentality and culture provides a hint of their original purpose: They follow their masters dutifully and loyally, the perfect soldiers. Much like an infant animal imprinting on its perceived parent, excavated warforged tend to recognize their discoverers as their masters. These masters are the ones allowed to give them orders and modify their objectives. However, as sentient beings, the warforged are also capable of learning from their experiences and (re-)interpreting their directives.
Spellcasters who have attempted to telepathically read warforged minds describe them as being a continual flowchart; essentially a warforged treats existence as a series of trained reactions to specific conditions or results, and falls back on simpler actions (a.k.a. combat) when faced with unfamiliar scenarios. Theoretically one can eventually live long enough to develop sufficient algorithms to fully emulate a completely sentient being.
The fact that someone made them this way is very unsettling to many scholars.
Mechanically they're the same as the warforged released in Unearthed Arcana. I've just established their fluff as FUCKING MEDIEVAL ROBOTS because who the hell buys that 'living construct' bullshit anyway?
Maybe the hard questions happen if someone drags Eberron into Aetheria…
Peg source: Deviantart.