I kind of assumed that the expression “wonder weapon” implied air quotes. AFAIK, the term is a calque of “Wunderwaffe,” and dates back to WWII. Most of the wonder weapons didn’t work, or were rushed into production without adequate engineering or testing, and proved to be disappointments.

Thus, I have always associated the term with something that is developed in the hope of changing everything, but ultimately serves only for propaganda.

https://en.wikipedia.org/wiki/Wunderwaffe