Order ye the buckler and shield, and draw near to battle.
Derisive summons to battle. With all your mighty preparation for the invasion of Nebuchadnezzar, when ye come to the encounter ye shall be "dismayed" (Jeremiah 46:5). Your mighty threats shall end in nothing.
Buckler - smaller, and carried by the light-armed cavalry.
Shield - of larger size, and carried by the heavily-armed infantry.