The whole Mahaabhaarat revolves around Kaurav and Paandav. Although all Paandav were of Divine birth, but still Arjun was special among all of them. he was so special that even Krishn has said in Geetaa that among Paandav He is Arjun. If you are thinking that he might be special in one or two or three ways, you are thinking still at a very low level. He had several special characteristics.
Arjun's Special Characteristics
We start his special characteristics from his birth and then proceed from there --
(1) Arjun was a part of Naaraayan
Arjun was not only the son of Indra, but he was the incarnation of Nar and that is how he was the part of Naaraayan. Ad that is why Krishn was right. He was Arjun among Paandav. WHY? Dharm had a son named Naaraayan. Naaraayan produced Nar from His own body and that is how there were Nar nad Naaraayan - both were one. Both did penance for long time in Badaree forest. This shows that Arjun was a part of Krishn. That is why Krishn said - "Among Paandav I am Arjun."
(2) It was only Arjun who was lucky enough to hear Geetaa from God's own mouth and see God's Viraat Roop with his own eyes. Sanjaya's case is different.
(3) Arjun could use his both hands to shoot arrows.
(4) He was so fast i shooting arrows, that when his one bow string was broken people could not see him changing the bow string. All they could see the circle made by pulling the string of his bow while shooting the arrow.
(5) He never lost any battle, except two - one was from Shiv, and he other one from his son, but that was because of a curse. That is why his one name was Vijaya.
(6) As Nar he had the control over Apsaraa and water. One should know that Apsaraa are born from water. The examples of his control over Apsaraa and water are --
----When he was only a child he saved Drone from the water creature crocodile
----When he became young His prowess over water while he was burning Khaandav forest - Indra made rain fall over it to put out the fire .... but he succeeded to stop that water...
----When he was in Heaven to take Divine weapos, he could restrain over Urvashee - the most beautiful Apsaraa of Indra's court. She was the same Apsaraa after whom his ancestor Pururavaa was so mad
----He rescued five Apsaraa who were living in water in the form of crocodile from curse.
----He brought water for Bheeshm too when he fell in the battlefield and asked for water
(7) He had full control over Kaam
----He remained calm when Uloopee abducted him to her Naag Kingdom under water.
----He had full control over Kaam, as he had control over Kaam Dev's vehicle crocodile too - Drone incident and the rescue of five Apsaraa in crocodile form.
----Because he had full control on Kaam that is why Drone considered him a worthy person to learn Brahmaastra. Ashwatthaamaa could not learn it in full and he was jealous with Arjun on this matter.