Except as provided in subsection (b) of this section, the Secretary, or the Deputy Secretary with the approval of the Secretary, may exercise any power, duty, responsibility, or function of any unit, unit head, or appointing officer in the Department. The Secretary or the Deputy Secretary may not exercise a power, duty, responsibility, or function that is set forth in: §§ 7–204(b)(2), 7–205(a), and 7–401 of this article; or Title 10, Subtitle 3 of this article.