"vexing" is defined as "annoying, worrying, or causing problems" [1]. I have encountered the word hundreds of times, but until your comment I wasn't aware that it was used in a magical context too.
If you look up a linguistics corpus like the Corpus of Contemporary American English [2] or the British National Corpus [3] -- visit those sites, search for "vexing", and click on "VEXING" again -- you'll see a representative set of usages of the word "in the wild", and none of them appear to have anything to do with magic. There's also something in C++ called the "most vexing parse" [4], which too doesn't seem to have anything to do with magic. (By the way, you may like to try this exercise with "ritual" too, to see how the word is used in practice.)
[1]: https://dictionary.cambridge.org/us/dictionary/english/vexin...
[2]: https://corpus.byu.edu/coca/
[3]: https://corpus.byu.edu/bnc/
[4]: https://en.wikipedia.org/wiki/Most_vexing_parse