Duryōdhana who had expressed his lament in the presence of Drōṇa did not do so secretively. Bhīṣma was nearby. He spoke to Drōṇa in such a way that it should be audible to Bhīṣma. How might it have affected Bhīṣma!
His grandson has been expressing dissatisfaction about him to Drōṇa. He himself, disregarding his status as a veteran, and solely in deference to the throne, had assumed leadership at the battlefront; much against his own conscience. He remained a bachelor, sacrificing all his pleasures and ambitions, relinquishing his right to ascend the throne, in order to protect the royal seat. If not, Bhīṣma had the rightful claim to the throne. Concerning such a Bhīṣma, who had sacrificed everything in honour of the throne, were the taunts of his own grandson. How agonizing is this to him!
How should he get the message across to this fool, that he has come to the war front in all sincerity, he has aside his own interests, bound by his deference to the royal decision? This cannot be expressed through speech. Therefore, Bhīṣma chose to express it through action itself, as revealed in the next ślōka –
तस्य  सञ्जनयन्हर्षं कुरुवृद्धः पितामहः |
सिंहनादं विनद्योच्चैः शङ्खं दध्मौ प्रतापवान् ||१२||
tasya sañjanayanharṣaṁ kuruvr̥d’dhaḥ pitāmahaḥ |
sinhanādaṁ vinadyōccaiḥ śaṅkhaṁ dadhmau pratāpavān ||12||
[To cheer him, the veteran grandfather of the Kuru clan, the most gallant one, let out a powerful lion’s roar and blew his conch].
In the nine ślōkas preceding this, Duryōdhana had poured out the utmost of his grief. To one who started off in the spirit of gain only through war, even as the war was to commence, is now depressed, fearing defeat. Though Bhīṣma was internally joyous on this development, as the commander of the forces he had to perform his duties. He had to drive away the sorrow that filled Duryōdhana and inspire him. It is thus that he produced a magnificent sound that would make even a youngster shy. This battle roar was a stand-out inspiration for the entire army. The high pitched lion’s roar moved the entire army, spelt the commencement of war and also the customary sounding of the conch. When the commander sounds the conch, it calls for war-readiness, symbolising that the battle is about to commence. His lion’s roar was great: conch sounded was of high decibel. Even a very ordinary soldier too would be charged with valour. In this way, to be applicable to both sides is the term ‘उच्चैः(uccaiḥ)’ used in the middle ‘सिंहनादं विनद्य उच्चैः शङ्खं दध्मौ (sinhanādaṁ vinadya uccaiḥ śaṅkhaṁ dadhmau) [‘सिंहनादं उच्चैः विनद्य शङ्खं उच्चैः दध्मौ (sinhanādaṁ uccaiḥ vinadya śaṅkhaṁ uccaiḥ dadhmau)].
Unsurpassable in courage, Bhīṣma’s lion’s roar, the conch sound, both were dignified enough to inspire all those who had lost courage to face the war. That is how Bhīṣma is referred to as ‘प्रतापवान् (pratāpavān)’ in the Gītā.
Initially there are adjectives relating to his age – कुरुवृद्धः and पितामह (kuruvr̥d’dhaḥ and pitāmaha).
He was the senior most of the Kuru dynasty. There was none as aged, senior, experienced as him in the Kuru dynasty.
In reality there were people older than Bhīṣma in that army. The king of Bahlīka was Śantanu’s elder brother. Bhīṣmācārya’s paternal uncle. Bahlīka’s son Soma Dutta was about as old as Bhīṣma. Might have been slightly older too. But none of them remained to be the senior members of the Kuru dynasty by now. Being adopted by the king of the Bahlīka kingdom, he was popularly known as Bahlīka himself. Or that country itself came to be known as Bahlīka from him. His daughter Rōhiṇi was Vasudeva’s wife – Balarāma’s mother. In this way Bhīṣma’s uncle separated from the Kuru dynasty and joined the Bahlīka dynasty. For now, it was just Bhīṣma that was the senior most within the Kuru dynasty.
Not just senior, he stood as the grandfather of the Kauravas, he sacrificed his entitlement to the throne and brought them up. Not just for the Kauravas alone, but he came to be regarded as the ‘grandfather of the entire Kuru dynasty,’ a great person who had earned their love and respects, as the grandfather.
These two adjectives which point to the greatness of Bhīṣma, also simultaneously bring out the meanness of Duryōdhana. In the front of such a great person of the dynasty, on whose lap he had grown up, in the presence of such a grandfather, the grand son Duryōdhana spoke those deceptive words! There was no end in sight to his imprudence.
When stated to be at such a ripe old age, that none should have doubts about his ability, unlike what Duryōdhana did, is why he has been called as ‘प्रतापवान् (pratāpavān)’ at the end of the ślōka. It is true that in terms of age he is old; but, his valour had not aged. In those times, there was no youngster who could have been valorous enough to claim that he could challenge him and win. He was an incomparable brave one who had overcome aging through yogic powers. His daring could only be compared to his own daring. ‘प्रतापवान् (pratāpavān)’ has the power to convey these many meanings – ‘प्रतापवान् (pratāpavān)’ – one who possesses enormous courage; one who possesses an undiminishing courage at all times; one who came to be eulogised as the one possessing great valour in those times.
Even so Duryōdhana did not believe in the sincerity of this grandfather. Even though he had seated Bhīṣma in the seat of the commander of his army, he goes to Drōṇa to express his grief. To this boy [though he was a regarded as a boy by Bhīṣma, his age at that juncture was 71 years]. To inspire was the duty of the commander in chief – तस्य सञ्जनयन्हर्षं (tasya sañjanayanharṣaṁ). It is for this that he sounded his lion’s roar and conch.
कुरु+वृद्धः(kuru+vr̥d’dhaḥ) – the elder one of the Kuru dynasty; प्रतापवान् (pratāpavān) – greatly courageous; पितामहः (pitāmahaḥ) -the grandfather Bhīṣmācārya; तस्य (tasya) – to that Duryōdhana; हर्षं (harṣaṁ) – cheer; सञ्जनयन् (sañjanayan) – bringing; उच्चैः (uccaiḥ) – forcefully; सिंह+नादं(sinha+nādaṁ) – lion like roar; विनद्य (vinadya) – done; उच्चैः (uccaiḥ) – forcefully(intensely); शङ्खं (śaṅkhaṁ) – conch; दध्मौ (dadhmau) – blew.
* * *
 Between ślōka no.11 ‘अयनेषु च सर्वेषु (ayanēṣu ca sarvēṣu)’ and this ślōka no.12 following it, some people recite three additional ślōkas –
अथोच्चैः संप्रहृष्टत्मा युक्तः शान्तनवोऽब्रवीत् ।
प्रीतिमान् हि दृढं कृष्णः पाण्डवेषु यशस्विषु ॥१२॥
तस्माद बिभेमि राजेन्द्र शमो भवतु पाण्डवैः ।
पृथिवीं भुंक्ष्व सहितो भ्रातृभिर्बलिभिर्वषी ॥१३॥
नरनारायणौ देवाववज्ञाय नशिष्यसि ।
इत्येवं कथयन् राजन् भीष्मः शान्तनवो महान् ॥१४॥
(athōccaiḥ samprahr̥ṣṭatmā yuktaḥ śāntanavō̕bravīt ।
prītimān hi dr̥ḍhaṁ kr̥ṣṇaḥ pāṇḍavēṣu yaśasviṣu ॥12॥
tasmāda bibhēmi rājēndra śamō bhavatu pāṇḍavaiḥ ।
pr̥thivīṁ bhuṅkṣva sahitō bhrātr̥bhirbalibhirvaṣī ॥13॥
naranārāyaṇau dēvāvavajñāya naśiṣyasi ।
ityēvaṁ kathayan rājan bhīṣmaḥ śāntanavō mahān ॥14॥)
तस्य सञ्जनयन्हर्षं (tasya sañjanayanharṣaṁ)-
These ślōkas, as seen earlier, are not in agreement with Gītā’s psychology and if these three are added, in all there would be 703 ślōkas. This does not correspond to the name of ‘सप्तशति (saptaśati)’ that is given to Gītā. Therefore, it would be in order to say that these are extraneously inserted ślōkas.