和英辞書

鎧袖一触

phrase

to defeat an opponent in a single blow

彼はその試合で鎧袖一触の勝利を収めた。

He achieved a victory in that match by defeating his opponent in a single blow.

意味（1）

to defeat an opponent in a single blow

2011, Craig L. Symonds, The Battle of Midway, Oxford University Press, page 179

Instead, Genda Minoru, the resident strategic genius, replied with a boast: "Gaishu Isshoku". Literally this means "One touch of the armored gauntlet"; idiomatically, it connotes an easy victory.