इत्यर्जुनं वासुदेवस्तथोक्त्वा स्वकं रूपं दर्शयामास भूयः। आश्वासयामास च भीतमेनं भूत्वा पुनः सौम्यवपुर्महात्मा ॥

ity arjunaṁ vāsudevas tathoktvā svakaṁ rūpaṁ darśhayām āsa bhūyaḥ āśhvāsayām āsa cha bhītam enaṁ bhūtvā punaḥ saumya-vapur mahātmā

Vâsudeva, having thus spoken to Arjuna, again manifested His own Form, and consoled the terrified one, the Mahâtman again assuming a gentle form.

In plain words: Sanjaya, the narrator, says that Krishna (called Vasudeva) then took his own gentle form again. The great-souled one comforted the frightened Arjuna.