The story I have in mind is called "Monarchy".
Story: Millennia ago all life in the galaxy was driven to the verge of extinction by a rogue artificial intelligence, a cosmic entity that is currently referred to as the "Unnamed One" in superstitious tones. In response, all biological life forms established a galactic government known as The Monarchy. The cardinal rule of which is that no space faring civilization could be reliant upon artificial intelligence and mechanical technology over biological equivalents. Now humanity is beginning to colonize, and the Monarchy has discovered it is a species in complete violation to their proscriptions. In response, they have given humanity an ultimatum - either they can submit unconditionally to the imperium and give up their heretical technologies, or the deviant species can face complete annihilation. As bizarre, bio-ships are reported at the edge of human space, with weapons and abilities never even imagined, a small military team raids a pirate ship to find a strange artifact, a sentient weapon that can change the tide of war. However this weapon may be perhaps more dangerous then the Monarchy itself - as it is nothing less the Remnant of the Unnamed, sent by unknown agents and transferred into a humanoid body. The Monarchy is not unaware of this, and has sent one of their oldest weapons - a living weapon, capable of crushing tanks or disguising itself as an ordinary person at will.
I am new to this site. This would be my first.