Of the three he was honored above the two, and he became their commander, but he did not attain to the three.
Note. The Hebrew distinguishes two groups of three: Abishai was chief of the second group, but he did not attain to the first. Without that key the reckoning of “the three… the two… the three” cannot be followed.
In context
19and said, “Far be it from me, before my God, to do this! Should I drink the blood of these men, who risked their lives? For at the risk of their lives they brought it.” So he would not drink it. These are the things the three mighty men did. 20Abishai, the brother of Joab, was chief of the three; he raised his spear against three hundred slain, and he had a name among the three. 21Of the three he was honored above the two, and he became their commander, but he did not attain to the three. 22Benaiah son of Jehoiada, son of a valiant man of many deeds, from Kabzeel — he struck down the two Ariel of Moab, and he went down and struck down a lion inside a pit on a day of snow. 23He also struck down an Egyptian, a man of great size, five cubits tall; in the Egyptian’s hand was a spear like a weaver’s beam, but he went down against him with a staff, wrenched the spear from the Egyptian’s hand, and killed him with his own spear.