a man plucked off: This custom does not refer to the law about refusing to marry a brother's widow, but was usual in the transfer of inheritances. For this relative was not a brother, but simply a kinsman; and the shoe was not pulled off by Ruth, but by the kinsman himself.
The Targumist, instead of his shoe, renders "his right hand glove," it probably being the custom, in his time, to give that instead of a shoe. Jarchi says, "When we purchase anything new, it is customary to give, instead of a shoe, a handkerchief or veil."