What does Judges 5:29 mean?

Deborah's song (Judges 5:1) is nearing its end. She has recorded the Lord's victory over the Canaanites (Judges 5:19–22) and the death of the general Sisera at the hand of a woman while he slept (Judges 5:24–27). Now, in a sense, Deborah celebrates the grief of Sisera's mother as she waits for the son who will never return (Judges 5:28). The reason for this crowing is driven by Sisera's long oppression of Israel (Judges 4:1–3) as well as details given in these verses. These indicate Sisera was not merely an oppressor, but an especially cruel and fearful one (Judges 5:30).

As depicted here, Sisera's mother stands at the window, crying and looking for her son. She asks why she has not yet heard or seen his chariot. The other royal ladies express the same concern. Here, Deborah seems to sarcastically refer to these women as "wise," as they are completely wrong in their assumption. In the next verse, the mother and princesses assume Sisera is late because he has so much captured loot to divide—including women, crassly referred to in the Canaanite city as "wombs."