Tough question. It could be that contour here means a well-defined image and brisk means sharp. So a concrete identity rather than the 'quasi' and 'unfinished' people/objects/whatever subjects of the poem. Here's that poem in full in case anyone else has any other ideas.
What shall I give my children? who are poor, / Who are adjudged the leastwise of the land, / Who are my sweetest lepers, who demand / No velvet and no velvety velour; / But who have begged me for a brisk contour,
Crying that they are quasi, contraband / Because unfinished, graven by a hand / Less than angelic, admirable or sure.
My hand is stuffed with mode, design, device. / But I lack access to my proper stone / And plenitude of plan shall not suffice / Nor grief nor love shall be enough alone / To ratify my little halves who bear / Across an autumn freezing everywhere.......