Noble Phantasm is a nice Fate reference, but that is a term very specific to Fate, it literally means nothing out of context. Keeping it as something like divine tool or something makes much more sense.
Not since Chapter 33 Page 9, where they say your level can generally only be uncovered in a Church. And that it's usually Secret Personal Info, not to be revealed to others. Tohru only learns about the Lost Person Level Cap in Chapter 35. So it's a mix of, he has crazy powers not really correlated to Levels, and that it's uncouth to ask about it.