Administrators with the will annexed shall have the same authority as the executor named in the will would have had, and their acts shall be as effectual for every purpose: PROVIDED, That they shall not lease, mortgage, pledge, exchange, sell, or convey any real or personal property of the estate except under order of the court and pursuant to procedure under existing laws pertaining to the administration of estates in cases of intestacy, unless the powers expressed in the will are directory and not discretionary, or said administrator with will annexed shall have obtained nonintervention powers as provided in chapter
11.68 RCW.