Where the shape comes from
A broad-bladed axe standing upright on its handle — early oracle bone forms show the blade of an implement, taken as the badge of the man capable enough to wield authority; a later folk reading, still repeated in the classical dictionaries, parsed it instead as one stroke able to multiply ten, a scholar being someone who reasons the many from the few. It names men of standing in 战士, a soldier, and 进士, a scholar who has passed the highest imperial examination, and lends its shape to 壮, robust, vigorous.
汉字 filed under 士
No published character on HSK Guide is filed under this radical yet. 汉字库.