The homunculus, the so-called "artificial hero".

An artificial, intelligent creation, greater than its constituent materials, capable of learning and self-improvement at a rate faster than any natural-born human, no matter how refined their bloodline may be.

It's terrifying less because of raw power, and more because it comes into play at a point in history when all of the great heroes have slaughtered one another in an equivalent to a world war.

The homunculus in question is a walking insult to the nations that "won" this war on paper, because it threatens to topple the systems of power and caste that they have set up just by existing.

What's the point of kowtowing to the remaining heroic bloodlines when we, the normal people, can just remake ourselves to be like the homunculus and bring the oppressive regime toppling down atop the nobles' heads?