Yuuki's just confusing himself😅. All his questions about the Lord of Nosferatu are so easy to answer. It's the command unit, the Lord of the Lords, the Lord of Everything. It wasn't made for someone like him, it was made for him for when he returned. They were able to configure it with his blood because there are those in the village with his blood. His own people built the lords. See? Super easy to asnwer. Yuuki gets super dumb sometimes.
Thing is they stole it, not made it so it's as you say the commanding unit for the big brass in the organization, probably packed with tools to control other lords in case of a rebellion and the best unit. I find his obliviousness to be spot on character, as an immortal that barely interacted with civilization(the village was an anomally), he doesn't know how nobility and organizations work, he probably thinks that the best fighter should have the best machine.
Personally, I think it's a bit of Column A, and a bit of Column B.
I'll admit, I kinda thought as Odious1 did at first. But then as you made your argument, I realized that yes, Odious1's idea is simple. Too simple, even.
But there's a possibility that lays neatly in the middle.
No, it was indeed
not made for him. And no, Lyle was not responsible for it being made. But I'm sure he played a significant role. And it's easy to guess what that role was to be: he was to be it's primary operator.
You have to remember, Lyle and Remilia were working toward getting themselves as deeply embedded into the Elysium Temple as possible so they could better orchestrate their downfall. And Lyle was already considered trustworthy since he killed Yuuki in his previous life. You could even say that he was the Hero of the Elysium Temple. It also helps that he was, by and large, a very competent fighter, so it would only make sense that the Elysium Temple would pick him to be the operator of their greatest and most powerful Lord.
With that, it would have been incredibly easy for Lyle to set everything up for Yuuki. Seeding it with the Mystel Blood, stealing it, hiding it away in a manner that only Yuuki would be able to discover, and ultimately setting it up so Yuuki could use it right away if needs be.
After all, nothing gives a hacker more power than having direct access to the hardware itself.
Yuuki is just oblivious because he's not giving Lyle enough credit, or even realizes just how far up the ranks in the Elysium Temple he managed to get. Though I'm sure that a fair bit of that was Remilia plotting and scheming in the background. And Yuuki is gonna be utterly gobsmacked once he realizes what Lyle and Remilia did.