I haven't seen the raws but I guess "noble" is translated from 尊い in which case that's otaku slang and doesn't really mean "noble".
Going back to this, because I think I ought to have explained that what I mean about it being otaku slang is that in the last few years it has emerged as being a generic way to praise yuri stuff (and other otaku stuff, such as idols). To some extent it's like it has usurped "moe", which is dated now. And I don't think "moe" really fit all that well with yuri so it seems like it was especially easy for something else to take hold among yuri fans. So you could translate it as "precious" or something along those lines, but the word choice is more because it's a meme, rather than it being chosen for the word's real meaning.