I remain with the idea that such reciprocate mechanism was more intended to unfold that to fold... pass the preciosity.
As if i was wandering on a fantasy when trying to decipher the attribution of the term "attack", HERE
you have an interesting French description of the "garde tournante" in that, even not dominating the language, one may catch a pretty good idea of how english speaking collectors arrived at such term ... attack = combat
Roughly translating ...
"The brass guard has two parts, from which one, swiveling, passes from normal
position to combat
position, by a simple 90º rotation".