| Gill's Exposition of the Entire Bible How are the mighty fallen,.... This is the burden of this elegiac song, being the third time it is mentioned: and the weapons of war perished! not only the valiant soldiers were killed, but their arms were lost; and particularly he may mean Saul and Jonathan, who as they were the shields of the people, so they were the true weapons and instruments of war, and with them all military glory perished; which must be understood as a poetical figure, exaggerating their military characters; otherwise David, and many mighty men with him, remained, and who revived and increased the military glory of Israel, as the following history shows.
Keil and Delitzsch Biblical Commentary on the Old TestamentThe third strophe (2 Samuel 1:27) contains simply a brief aftertone of sorrow, in which the ode does away: Oh how are the mighty fallen, The instruments of war perished! "The instruments of war" are not the weapons; but the expression is a figurative one, referring to the heroes by whom war was carried on (vid., Isaiah 13:5). Luther has adopted this rendering (die Streitbaren).
Geneva Study BibleHow are the mighty fallen, and the weapons of war perished!
Matthew Henry's Concise Commentary1:17-27 Kasheth, or the bow, probably was the title of this mournful, funeral song. David does not commend Saul for what he was not; and says nothing of his piety or goodness. Jonathan was a dutiful son, Saul an affectionate father, therefore dear to each other. David had reason to say, that Jonathan's love to him was wonderful. Next to the love between Christ and his people, that affection which springs form it, produces the strongest friendship. The trouble of the Lord's people, and triumphs of his enemies, will always grieve true believers, whatever advantages they may obtain by them. | 
