In fact, even a Machine Priest could not control machinery remotely.
Since it was machinery, it had to follow the rules of machinery. Humans needed an entire control system, along with steel transmission mechanisms and a power source, to make machinery move according to their will.
The Path of the Reforging Flame merely replaced some of those components with supernatural power. For instance, using Spirituality as a medium to instill human will into machinery was essentially just pressing buttons with Spirituality.
What Elliot had done, however, was make an absurd demand that violated this world's laws of physics. How could a mechanical arm with neither a power source nor a connection to a control system possibly move?
You could push it with Spirituality or pull it up with the Formless Art, but you could not simply order it to move on its own out of thin air.
These were the physical laws of this world. They never listened to reason.
Unfortunately, another machine was equally unreasonable, and its priority was always the highest.
The Difference Engine's settings conflicted with the laws of physics, so the world modified itself and obeyed its command.
Elliot blinked. He seemed to have seen the machine before him shift slightly.
Was it an illusion?
Fortunately, he could not move right now, so he had all the time and patience he needed to try. Little by little, he tried activating his Spirituality and experimented in various ways, until he finally found the ability that triggered it:
[Compliance]: You can control Vessels.
This was the Talent he had selected for Vanessa. At the time, he had been full of confidence that it would definitely prove useful, only to discover that these [Vessels] were even harder to find than he had imagined.
Dream Creatures did not