One wonders what precisely those agreements look like, especially after the Ragnarok. Especially since Muspelheim seems like it's looking to forge alliances in Midgard.
At any rate, I was somewhat more concerned with the breadth of an Aes' power, rather than the depth. I've always considered the UF-Aesir to have something of an unconscious rapport with their portfolio, over and above conscious command, with or without limiters. So instead of Corwin asking it to do something, the thing, on some ill-defined, metaphysical level, recognizes him, and does him a favor, so to speak.
For instance, somewhere, I can't remember where, some observer sees Corwin praying, and wonders whether it would actually help, or something to that effect. How much of that is Corwin being a Aes in general, Corwin being his mother's son, or Corwin being the Aes of the Great Machines? Where does the Aes end and the engineer begin?
(These are mostly rhetorical.)
Also, Futureshock is one of my favorites, because of that "coiled serpent" aspect, that Largo is so utterly outclassed.