‘ And he said to them, “What have I done in comparison with you? Is not the gleaning of the grapes of Ephraim better than the vintage of Abiezer?” '
Gideon revealed that he had learned from his wise father. He did not try to argue the position, or point out that Yahweh alone had received any glory from the victory. Rather he pointed out to them how successful they had been. He and his men had not captured any Midianite royalty whereas Ephraim had captured two. He and his men had only picked up commoners whereas Ephraim had picked up and brought to him the heads of royalty.
The gleaning is the leftovers picked up from the fields when the reapers have gone by, an accurate picture of the work of Ephraim. But in that gleaning were the royal princes and a considerable number of the enemy. The victory as a whole had been Yahweh's. The vintage of Abiezer were merely the lingerers from among the fleeing enemy.
On the other hand Ephraim had met them full on at the fords and had reaped amply, including the princes. The importance attached in those days to the killing of the chiefs is brought out in that Barak lost to a woman the right to kill Sisera and it was counted as a great loss (Judges 4).
“Abiezer” probably refers to Gideon himself rather than to the content of the three hundred, although it could be that the test had separated out the locals who knew about the leeches. Compared with Ephraim he had received little honour as yet.