In such proceedings the Director may refuse to register the opposed mark, may cancel the registration, in whole or in part, may modify the application or registration by limiting the goods or services specified therein, may otherwise restrict or rectify with respect to the register the registration of a registered mark, may refuse to register any or all of several interfering marks, or may register the mark or marks for the person or persons entitled thereto, as the rights of the parties under this chapter may be established in the proceedings. The authority of the Director under this section includes the authority to reconsider, and modify or set aside, a decision of the Trademark Trial and Appeal Board: Provided, That in the case of the registration of any mark based on concurrent use, the Director shall determine and fix the conditions and limitations provided for in subsection (d) of section 1052 of this title. However, no final judgment shall be entered in favor of an applicant under section 1051(b) of this title before the mark is registered, if such applicant cannot prevail without establishing constructive use pursuant to section 1057(c) of this title.