In my pennyworth pulp-paper "Dictionary of Difficult Words" published by Wordsworth I found the word "diasyrm n rhetorical device of damning with faint praise" which became an immediate favourite.

I knew the phrase "damnation with faint praise" all too well, and was happy to discover that there is actually a word for it.

It was an epiglottis moment.

Sadly, all attempts to discover its etymology have come to nothing.

Does any know, or can anyone take an educated guess, at its root, cognate, origin?