I'm not sure what your point is, since you looked at the vanishingly uncommon phrase alone, giving the false impression of popularity.
You also need to keep in mind what Google Ngram is.
https://books.google.com/ngrams/info
>> "When you enter phrases into the Google Books Ngram Viewer, it displays a graph showing how those phrases have occurred in a corpus of books (e.g., "British English", "English Fiction", "French") over the selected years."
It's a collection of books. Books remain relevant, but it tells you nothing of usage outside that. You only have to run a search on Google to see that it's used in a wide range of unrelated contexts. It's not some obscure anachronism or regionalism.
It isn't. "Grow weary of" is a common phrase. "Grow wary of" are words you can put together, but it's not a common phrase.
I've already posted all the evidence needed, and I grow weary of this misguided argument.
Here, I'll give you a head start on doing what I suggested.
https://www.google.com/search?q=%22grow+wary%22
That sure looks like a phrase used across a wide range of contexts and unconnected fields, too wide to support any notion that it's obscure. There's even a non-English news outlet using it in its English coverage.