For the first time in the chapter, Arjuna stops describing and starts pleading. The fanged mouths blazing like the fire at the end of time — 'kalanala,' the fire of cosmic dissolution — have broken something in him. He cannot tell north from south. He cannot find shelter anywhere. So he does the only thing left: he asks for grace.
The plea 'Prasida' — be gracious — is one of the most intimate words a devotee can speak. It is not a demand. It is not a negotiation. It is the sound of someone who has run out of resources and turns entirely to the one who holds everything. A lost traveler does not argue with the storm; he seeks shelter.
Arjuna uses two addresses here: 'Devesha' (Lord of the devas) and 'Jagannivasa' (the one in whom the universe dwells). Both are expressions of surrender. He is not speaking to a friend anymore. He is speaking to the power that contains all of existence — and asking that power to be kind.