The narrator returns. Sanjay, sitting far from the battlefield, tells the blind king Dhritarashtra: "Having spoken thus, O King, the great Lord of Yoga, Hari, revealed to Arjuna his supreme majestic form." The sentence is simple. The event it describes is anything but.
Sanjay calls Krishna 'Mahayogeshvara' — the great Lord of all Yoga. And 'Hari' — the one who removes suffering. These are not ornamental titles. They tell Dhritarashtra exactly who his nephew's charioteer really is. Whether Dhritarashtra absorbs the implication is another matter entirely.
This shloka is a hinge. Everything before it was conversation — Arjuna asking, Krishna agreeing. Everything after it is vision. The words stop and the showing begins.