The affix ṭhak comes after a word in the Accusative -2nd case in construction when the sense is 'who gleans that'.,
Thus बदराण्युञ्छति = बादरिकः 'who picks up jujubes'. श्यामाकिकः, काणिकः ॥ To pick up every grain (कण) fallen on the ground is called उञ्छ ॥,