John Gill Commentary 2 Samuel 23:19

"Was he not most honorable of the three? therefore he was made their captain: howbeit he attained not unto the [first] three." — 2 Samuel 23:19 (ASV)

Was he not most honourable of three ?
&c.] He was; who, besides the exploit here mentioned, did many other things; he went down with David into Saul's camp, and took away his spear and cruse, which were at his bolster, (1 Samuel 26:6–12) ; he relieved David when in danger from Ishbibenob the giant, (2 Samuel 21:16 2 Samuel 21:17) ; he beat the Edomites, and slew eighteen thousand of them in the valley of salt, (1 Chronicles 18:12) :

therefore he was their captain ;
of the other two, or was head over them, took rank before them:

howbeit he attained not unto the [first] three ;
for fortitude, courage, and warlike exploits, namely, to the Tachmonite, Eleazar, and Shammah.