First and foremost he is ensuring the fighter is lucid and responsive.
First thing he does is grab the gloves and wipe the knuckle area(s) on his shirt as they likely picked up some dirt/sand/debris from the ring floor.
He often requests the fighter tries to bring his hands up against resistance, expecting a decent push (if it is weak, he will end the fight).
He will instruct the fighter to bring his hands to the defensive position and reaffirm the fighter is lucid and in control.
During this whole thing (which takes only several seconds) he will maintain almost if not entirely unbroken eye contact.
A sharp, lucid fighter will stare him back down, confirm he is ready and able to continue when asked, and at the end of the 10 second count, he expects the “rattle” to all but disappear.
A fighter who needs to be excused from the contest will likely not display crisp movements and balance, wavering eye contact/gaze, and a drunken-like movement.