The Crucis is cybernetic control circuitry, extending the senses and the motor cortex to a machine. The Corvus is a ritual depilation which accompanies it.
Other cybernetics are very rare if not unknown. We can talk about reasons for that if you’d like. My guess is that they’re partly technological, partly cultural. Please start a new thread for that, though.
IRON without, IRON within
Now to keep this thread a little more on topic. Where does IRON originate from? Is it a recent invention made to facilitate the imperial society of the (uhm) Federation? It it a poorly understood relic of a lost golden age, faithfully reproduced for its incomparable ‘worth’?What threat was it buildt to counter?
It’s old, presumably evolving before the breakdown of the Federated Empires. It’s not poorly understood, it receives daily maintenance and upkeep. But the technologies involved are not well-understood in a wider context (that is, the Iron guilds understand and can recreate, refine and modify Avatar routines, but it would be a monumental undertaking to produce an entirely new intelligent agent like an Avatar but for a different purpose).
And, ah, what threat? What threat was a gun built to counter? How about a tank? Submarine? It’s this thing where humans have stuff, and generally either they want to keep that stuff, or they want to take someone else’s stuff. It sucks, but that’s how we live.