Chapter 7 gave me an idea regarding Jago's statement to Bren that Tano isn't licensed, versus his status in later books! Assuming it's not an outright lie -- and Tano does openly use a security radio in front of Bren, after the tourists have left -- perhaps Assassins must serve some sort of in-field journeymanship before becoming fully licensed.

It would explain both his familiarity with security equipment/methods and persons, his "clearances" the aiji mentions, and Jago's comment if he is a 'student' on the verge of graduating -- a top-level student, presumably, given his assignment to the aiji's household and long-held association with the Guildmaster.