Arjuna was devoted to his Guru . Though Drona taught everyone the same way, Arjuna excelled all others in skill. Drona was convinced that none of his other disciples could match Arjuna in skill in the use of arms. However, Drona adopted a trick to teach his own son Aswatama more than what he thought others. He would ask all his disciples to fetch water from the river. While he gave narrow-mouthed vessels to others, he would give a broad-mouthed vessel to Aswathama so that he could fill it fast and return earlier than others. In that time, Drona would teach his son several superior methods of using weapons.
Arjuna discovered this and got his narrow-mouthed vessel filled quickly by using the Varuna Astra (weapon) and managed to return at the same time as did Aswathama. He was thus able to receive the additional lessons that Drona gave his son. Drona soon became the favorite student of his Guru. Drona once secretly instructed his cook not to give food to Arjuna in the dark. However, one night when Arjuna was taking his food, the lamp was snuffed out by the wind. Arjuna continued to eat in the dark. This experience gave him the idea that he could do things in the dark also by cultivating a habit. So, he began to practice his bow in the night. Hearing the vibration of the bowstring, Drona came to him, embraced him and said, “I will do everything to make you an archer for whom there will be no match in this world."
After this incident, Drona began to teach Arjuna to fight sitting on the horse back, on the elephant and on the chariot and to fight from the ground. He also taught him the use of the mace, the sword, the lance, the spear, and the dart. He also taught him the art of fighting many men at a time by using multiple weapons.
Among the other disciples of Drona , Duryodhana and Bhima became skilled in the use of the mace. These two, however, were always jealous of each other. Aswathama excelled everyone in the mysteries of the science of arms. Nakula and Sahadeva became the best in handling the sword. Yudhishtira surpassed everyone else as a car-warrior. Arjuna, apart from excelling in the use of the bow, outshone every other disciple of Drona in intelligence, resourcefulness, strength, perseverance, devotion to the preceptor and other aspects. Accomplished in the use of all weapons, Arjuna became the foremost of even the foremost of car warriors. Among all the princes, Arjuna alone became an Atiratha (a car warrior capable of fighting at one time with sixty thousand foes). The sons of Dhritarashtra, finding that Bhima became endued with great strength and that Arjuna became accomplished in all arms, became very jealous of them.
One day Drona decided to test the accomplishment of his pupils. He had an artificial bird placed on the top of a tree and then called all his disciples. He told them, “Take your bows and aim at the bird. You should cut off the bird’s head with your arrow as soon as I give my command. I will give each of you a turn, one by one.”
He called Yudhishtira first. “Do you see the bird on the top of the tree?”
Yudhishtira said, “Yes, I do.”
Drona then asked him, “What do you see now, the tree, me or your brothers?”
Yudhishtira said, “'I see the tree, you, my brothers and the bird.”
Drona repeated his question but got the same answer.
Drona, dissatisfied with Yudhishtira’s answer said, “Step aside You can’t hit the target.”
He then called Duryodhana, then his brothers, then Bhima and then all others, one by one. Everyone gave the same answer as did Yudhishtira. Drona asked every one to step aside, one by one.
Finally Drona called Arjuna and gave him a similar command. When Arjuna stood aiming at the bird, Drona asked him, “Arjuna, what do you see, the bird there, the tree or me?”
Arjuna replied, 'I see only the bird, not the tree, or you.”
Drona told him, “Describe the tree to me.”
Arjuna said “I see only the head of the bird, not its body.”
On hearing these words of Arjuna, Drona felt that the hair on his body stood on end due to the delight experienced by him.
He then said, “Shoot.”
Arjuna let the arrow leave his bow instantly. The arrow struck the head of the bird on the tree and brought it down to the ground. Drona hugged Arjuna in admiration and delight.
Drona who was released from the clutches of the alligator after it was killed by Arjuna’s arrows was very much pleased with Arjuna’s alacrity and acumen. He then gave Arjuna the superior weapon Brahmastra. However he cautioned him against using it on any human being since the weapon had the potential to destroy the whole universe. He then blessed Arjuna saying, “'None else in this world will ever become a superior bowman to you. You will never be vanquished by any foe. You will achieve great things.”