13A. An Excise Officer appointed under section 13 shall exercise such powers and discharge such duties as are conferred or imposed on him by or under this Act; and he shall also be competent to exercise all powers and discharge all duties conferred or imposed upon any officer subordinate to him: Provided that, notwithstanding anything contained in this Act or the rules, the Board may, by general of special order, impose such limitations or conditions in the exercise of such powers and discharge of such duties as it thinks fit.