Jamieson, Fausset and Brown on Isaiah 22:2

2. art--rather, "wert"; for it could not now be said to be "a joyous city" (Is 32:13). The cause of their joy (Is 22:13) may have been because Sennacherib had accepted Hezekiah's offer to renew the payment of tribute, and they were glad to have peace on any terms, however humiliating (2Ki 18:14-16), or on account of the alliance with Egypt. If the reference be to Zedekiah's time, the joy and feasting are not inapplicable, for this recklessness was a general characteristic of the unbelieving Jews (Is 56:12).

not slain with the sword--but with the famine and pestilence about to be caused by the coming siege (La 4:9). Maurer refers this to the plague by which he thinks Sennacherib's army was destroyed, and Hezekiah was made sick (Is 37:36; 38:1). But there is no authority for supposing that the Jews in the city suffered such extremities of plague at this time, when God destroyed their foes. Barnes refers it to those slain in flight, not in open honorable "battle"; Is 22:3 favors this.