When man has made his words shining, and when he’s not alone among the others, then he could be appointed as sensei and, need not to teach nor assert it, the others will respect him.
No paper can state who is sensei: he’ll be raised and honoured by the ones who’ll respect him.
And the man will never quit from being a sensei, because the only way to abandon is to discredit himself in the eyes of those who elected him.