महाभारतः mahābhārataḥ - book-7, chapter-170, verse-20

शस्त्राकृतिभिराकीर्णमतीव भरतर्षभ ।
दृष्ट्वान्तरिक्षमाविग्नाः पाण्डुपाञ्चालसृञ्जयाः ॥२०॥

20. śastrākṛtibhirākīrṇamatīva bharatarṣabha ,
dṛṣṭvāntarikṣamāvignāḥ pāṇḍupāñcālasṛñjayāḥ.

20. śastrākṛtibhiḥ ākīrṇam atīva bharatarṣabha
dṛṣṭvā antarikṣam āvignāḥ pāṇḍupāñcālasṛñjayāḥ

20. bharatarṣabha śastrākṛtibhiḥ atīva ākīrṇam
antarikṣam dṛṣṭvā pāṇḍupāñcālasṛñjayāḥ āvignāḥ

20. O best of Bharatas, having seen the sky exceedingly filled with the forms of these weapons, the Pandavas, Panchalas, and Srinjayas became greatly agitated.

Words meanings summery:

• शस्त्राकृतिभिः (śastrākṛtibhiḥ) - by the forms of weapons, by weapon-shapes

• आकीर्णम् (ākīrṇam) - filled (with) (filled, covered, spread)

• अतीव (atīva) - exceedingly, greatly, very much

• भरतर्षभ (bharatarṣabha) - Addressing Dhritarashtra. (O best of Bharatas)

• दृष्ट्वा (dṛṣṭvā) - having seen

• अन्तरिक्षम् (antarikṣam) - sky, atmosphere, space

• आविग्नाः (āvignāḥ) - greatly agitated (distressed, agitated, frightened)

• पाण्डुपाञ्चालसृञ्जयाः (pāṇḍupāñcālasṛñjayāḥ) - the Pandavas, Panchalas, and Srinjayas

Words meanings and morphology

शस्त्राकृतिभिः (śastrākṛtibhiḥ) - by the forms of weapons, by weapon-shapes

(noun)

Instrumental, feminine, plural of śastrākṛti

śastrākṛti - form of a weapon, weapon-shape

Compound of śastra (weapon) + ākṛti (form, shape).

Compound type : tatpuruṣa (śastra+ākṛti)

• śastra – weapon, missile
  noun (neuter)
  Root: śas (class 2)
• ākṛti – form, shape, appearance
  noun (feminine)
  From ā-√kṛ (to make, form).
  Prefix: ā
  Root: kṛ (class 8)

Note: Agent of 'ākīrṇam'.

आकीर्णम् (ākīrṇam) - filled (with) (filled, covered, spread)

(adjective)

Accusative, neuter, singular of ākīrṇa

ākīrṇa - filled, covered, strewn, spread

Past Passive Participle

From ā-√kṛ (to scatter, spread).

Prefix: ā

Root: kṛ (class 6)

Note: Qualifies 'antarikṣam'.

अतीव (atīva) - exceedingly, greatly, very much

(indeclinable)

From ati (over, beyond) + iva (like). Adverbial.

Note: Intensifies 'ākīrṇam'.

भरतर्षभ (bharatarṣabha) - Addressing Dhritarashtra. (O best of Bharatas)

(noun)

Vocative, masculine, singular of bharatarṣabha

bharatarṣabha - best of Bharatas, chief of the Bharatas

Compound of bharata (descendant of Bharata) + ṛṣabha (bull, best).

Compound type : tatpuruṣa (bharata+ṛṣabha)

• bharata – descendant of Bharata, an ancient king
  proper noun (masculine)
• ṛṣabha – bull, best, chief, excellent
  noun (masculine)

Note: Addressed to Dhritarashtra by Sanjaya.

दृष्ट्वा (dṛṣṭvā) - having seen

(indeclinable)

Absolutive (Gerund)

From root dṛś (to see) with suffix -tvā.

Root: dṛś (class 1)

अन्तरिक्षम् (antarikṣam) - sky, atmosphere, space

(noun)

Accusative, neuter, singular of antarikṣa

antarikṣa - sky, atmosphere, intermediate space, ether

Note: Object of 'dṛṣṭvā'.

आविग्नाः (āvignāḥ) - greatly agitated (distressed, agitated, frightened)

(adjective)

Nominative, masculine, plural of āvigna

āvigna - agitated, distressed, disturbed, frightened

Past Passive Participle

From ā-√vij (to tremble, be agitated).

Prefix: ā

Root: vij (class 6)

Note: Predicative adjective.

पाण्डुपाञ्चालसृञ्जयाः (pāṇḍupāñcālasṛñjayāḥ) - the Pandavas, Panchalas, and Srinjayas

(proper noun)

Nominative, masculine, plural of pāṇḍupāñcālasṛñjaya

pāṇḍupāñcālasṛñjaya - the Pandavas, Panchalas, and Srinjayas (collective term)

Dvaṃdva compound of Pāṇḍu, Pāñcāla, and Sṛñjaya.

Compound type : dvandva (pāṇḍu+pāñcāla+sṛñjaya)

• pāṇḍu – descendant of Pandu (the Pandavas)
  proper noun (masculine)
• pāñcāla – a king or people of the Panchala country
  proper noun (masculine)
• sṛñjaya – a king or people of the Srinjaya tribe
  proper noun (masculine)

Note: Subject of the sentence (implied verb 'became').