I am curious about how 'fiddlestick' came to obtain the slanted meaning of 'nonsense'. Of all the researches I've conducted online(including etymology.com, phrasefinder, merriam webster), I find the explication on World Wide Words most nearly satisfactory
At some point in Shakespeare’s lifetime, it seems fiddlestick began to be used for something insignificant or trivial. This may have been because a violin bow was regarded as inconsequential or perhaps simply because the word sounds intrinsically silly. It took on a humorous slant as a word one could use to replace another in a contemptuous response to a remark. George Farquhar used it in this way in his play Sir Henry Wildair of 1701: “Golden pleasures! golden fiddlesticks!”. From here it was a short step to using the word as a disparaging comment to mean that something just said was nonsense.
Still I was wondering if there is a better supply of answer? Thank you.