The one word one is the big deal. Currently, it trumps any magus, any spell, any circuits, with absolutely no effort on his part. Plus it's aligned to no element. Thing would be waaaaaaaaaaaaay too common if it's that simple. It's basically a one-word answer to anything that any Master could do--defensive, environment-focused, not attacking him, etc.

... at least the bounded field one would immediately alert any magus that something's up, because their Servant would no longer be receiving mana.