«قد كانت البيض القواضب في الوغى / بواتر فهي الآن من بعده بتر»
The shining swords once cut decisively in battle; after him they have become blunted or bereft of their cutting force.
Bawātir begins the second hemistich and butr closes it. Both evoke the root b-t-r, while the thought moves from effective cutting to loss of that force.
The formal echo also reinforces the reversal in the meaning.