Belphegor the Mountebank was created in 1921.

Here's one:

Mountebank is a word.

Hoped this helped!

Mounterbarnks are fake so put it in I am a mountebank that does not help so think your self!

The Mountebank's Daughter - 1912 was released on:

USA: 23 December 1912

"Unction" is an oil or ointment; a "mountebank" is a charlatan or quack who sold patent medicines, so the unction of a mountebank is some concoction sold by this quack.

In the context of Hamlet (which I am guessing inspired this question), this is specifically an extremely deadly poison.