On the 17th day. Karna and Arjuna both fought the toughest battle of their lives and guess what?
Only one of the bows snapped! It was Gandiva. Not the Vijaya bow.
Pandava’s bowstring was being drawn with great force and snapped, with a loud noise. At that moment, the son of a suta struck Partha with one hundred kshudraka arrows. He pierced Vasudeva with sixty sharp iron arrows that were washed in oil and were tufted with the feathers of birds. They were like snakes that had cast off their skins.
At this, the Somakas ran away. Partha became extremely angry. His body was mangled by Karna’s arrows.
Source: Karna Parva Mahabharata critical edition.
Karna also cut off several strings of Gandiva. Arjuna however never ever managed to do the same.
O Partha! Radheya is destroying your arrows. Release supreme weapons.’ Using mantras, Arjuna released brahmastra. With those radiant arrows, Arjuna shrouded Karna. But Karna used extremely energetic arrows to angrily sever his bowstring. Fixing another bowstring, Pandava enveloped Karna with thousands of fiery arrows.
In that battle, when Karna severed his bowstring, he fixed another one so quickly that no one could make this out. It was wonderful. Using his weapons, Radheya countered all of Savyasachi’s weapons. At that time, his valour seemed to be greater than that of Partha.
Now some Arjuna bhakts have lined up to claim that Karna lost against Bhima with the Vijaya bow.
First if that’s the case, then Arjuna was also struck unconscious by Susharma. Arjuna was defeated when he held the Gandiva.
Having used his own shower of great weapons to sever the shower of arrows, Vasava’s son, the destroyer of enemy heroes, remained stationed on his chariot in the field of battle. O King! Susharma used arrows with drooping tufts to pierce Arjuna in the chest and pierced Arjuna in the chest and pierced him again with three other arrows. Having been severely wounded and pained, he sank down on the floor of his chariot. When he regained his senses, the one with the white horses, immeasurable in his soul and with Sri Krishna as his charioteer, quickly invoked the Aindra weapon.
Karna Parva: Chapter 1187(37)
Arjuna and several other Maharathas attacked Dronacharya and were defeated on the 11th day of the Kurukshetra war.
.Arjuna and Parshata, with their followers, surrounded him, together with all the maharathas—the Kekayas, Bhimasena, Subhadra’s son, Ghatotkacha, Yudhishthira, the twins, Matsya, Drupada’s son, Droupadi’s cheerful sons, Dhrishtaketu, Satyaki, the enraged Chekitana and maharatha Yuyutsu. O king! There were many other kings who followed the Pandavas. In accordance with their lineage and their valour, they performed many deeds. On seeing that the army of the Pandavas was thus protected in battle, Bharadvaja’s son glanced at them, with anger in his eyes. He was stationed on his chariot, invincible in battle, and was overcome by terrible rage. He pierced the Pandava army, like the wind scattering clouds. He attacked the chariots, horses, men and elephants in every direction. Though he was old, Drona roamed around, like a mad young man. His horses were crimson in colour and were as fleet as the wind. They were covered in blood. O king! Those horses thus assumed a beautiful appearance. On seeing that angry one, rigid in his vows, descend like death, the Pandava warriors fled in every direction. Some fled in fright.
Drona Parva Mahabharata critical edition.
Both warriors were defeated with supreme bows. So that point simply doesn’t matter
Yes! Gandiva has more statments on it’s side. But by feats Arjuna has also faced more defeats with Gandiva. Karna only used the Vijaya once and perfomed better than the wielder of Gandiva on the 17th day.
But either way the bow doesn’t really define the warrior as much. Karna performed well because he prepared himself well which allowed him to baffle of Arjuna’s weapons and afflict him.
All my points are from Vyasa’s Mahabharata.