Isaiah in chapter 11 speaks of a shoot . . . come out from the stump of Jesse (Is 11.1), which of course is a reference to Christ was was born from the line of David. It describes the qualities this Christ will have, since the anointing of the Spirit of the Lord will be on him:
His delight will be in the fear of the LORD.
He shall not judge by what his eyes see,
or decide by what his ears hear;
but with righteousness he shall judge the poor,
and decide with equity for the meek of the earth;
he shall strike the earth with the rod of his mouth,
and with the breath of his lips he shall kill the wicked (vv. 3-4).
The result of his coming will be a deep and enduring peace, one which will affect even the animal kingdom. In that most famous line, Isaiah affirms that the wolf shall live with the lamb (v. 6), undoubtedly a symbol of peace among peoples who've been reconciled through the messiah's wisdom, but perhaps even an evidence of cosmic transformation even including the animal kingdom.
Perhaps, moreover, implicit in the image of the peace between wolf and lamb is the notion that reconciliation will take place between victimized and victimizers. Lambs are peaceful animals generally, or at least such is my understanding. In any case, the later mentioned calves and little children (vv. 6-8) are certainly paradigms of peaceful creatures. Lions, wolves, asps, and leopards, on the other hand, are not. If we understand the image of peace among the animals as a symbol of reconciliation among human parties, we are intended to draw the inference that the wicked and violence-driven will be reconciled to their innocent victims.
But now if there is a reconciliation between parties, how can Isaiah speak of a slaying of the wicked? How does he say that when Christ comes, with the breath of his lips he shall kill the wicked (v. 4)? Certainly we never observe that to happen in the course of the gospel narratives; Christ, rather, is the one whom the wicked slay, and who nevertheless gives the Spirit to those who murder him (see Acts 2.36ff.).
I suggest we understand the "slaying" here along the same lines as we understand Paul's language about the death of the old self in Rom 6, Eph 4, Col 3, etc. The wicked will be slain by his words because they will change, they will repent in sack cloth and ashes and thus the wicked persons they once were will die away forever. If we interpret things this way, we do not lose the message of reconciliation implied in vv. 6-9. Other interpretations which propose a real slaying of the wicked lose this suggestion of repaired relations among human parties, however, to their disadvantage.