It was a fact that he (Arjuna) wanted to see them (those who joined the side of Duryodhana) to make an estimate of the strength which he had to face, although he was quite confident of victory because Krsna was sitting by his side. BG 1972 purports

Expressions researched:
"It was also a fact that he wanted to see them to make an estimate of the strength which he had to face, although he was quite confident of victory because Kṛṣṇa was sitting by his side"

Bhagavad-gita As it is

BG Chapters 1 - 6

It was an open secret that Duryodhana wanted to usurp the kingdom of the Pāṇḍavas by evil plans, in collaboration with his father, Dhṛtarāṣṭra. Therefore, all persons who had joined the side of Duryodhana must have been birds of the same feather. Arjuna wanted to see them in the battlefield before the fight was begun, just to learn who they were, but he had no intention of proposing peace negotiations with them. It was also a fact that he wanted to see them to make an estimate of the strength which he had to face, although he was quite confident of victory because Kṛṣṇa was sitting by his side.

BG 1.23 (1972), Translation and Purport

Let me see those who have come here to fight, wishing to please the evil-minded son of Dhṛtarāṣṭra.

It was an open secret that Duryodhana wanted to usurp the kingdom of the Pāṇḍavas by evil plans, in collaboration with his father, Dhṛtarāṣṭra. Therefore, all persons who had joined the side of Duryodhana must have been birds of the same feather. Arjuna wanted to see them in the battlefield before the fight was begun, just to learn who they were, but he had no intention of proposing peace negotiations with them. It was also a fact that he wanted to see them to make an estimate of the strength which he had to face, although he was quite confident of victory because Kṛṣṇa was sitting by his side.