The blessings of God through the Messiah have both corporate and individual implications as we see in the verse I quoted at the beginning. Interestingly this is not speaking about the time when the world is completely set to rights, when evil and death are vanquished, but rather sometime before that when Israel as a nation rests secure in God. Weapons of potential destruction and opposition continue to exist, but the servants of the Lord are confident in the face of them.
This prediction is in keeping with the blessings promised by God through Moses to Israel on the condition of their keeping his directives. What we see in the Book of Isaiah, especially the earlier chapters, are the consequences as warned by Moses for failing to do that. The promise of restoration and the resultant sense of security comes about, not on the basis of adherence to God's commands, which the people failed to keep, but rather due to God's deliverance through the Messiah.
The predictive elements of the biblical prophets are similar to looking at a far-off mountain range. Looking from afar we have a semblance of the complexity of the mountains, including some of its various peaks. Perhaps we can vaguely make out some vegetation and other aspects. It is only as we get closer to the mountain range that we begin to discover its detail, including its valleys, canyons, rivers, inhabitants, and so on. The discovery of the detail doesn't contradict the original view, it only clarifies it. The result of this clarification may give impressions very different from the original long-range view, but the difference in impression has more to do with our assumptions than the actual reality of the scene.
For example, the descriptions of God's restoration of Israel as spoken by Isaiah and the other prophets appear to refer to a particular single time period, but as history has unfolded we see that the actual details are more complex than originally anticipated. Specifically, it was assumed that when the Messiah would come, all the predicted blessings would happen in their fullness at that time. But instead the fulfillment of God's promises to Israel has been working out over a very long period of time.
What has occurred is that the promised reality has significantly, though partially, come about through Yeshua the Messiah. His resurrection is the foretaste of all the good things prophesied. While we still await the day when Isaiah's words will be completely fulfilled and Israel as a nation will rest secure in the midst of great opposition, we can know this kind of confidence right now through faith in Yeshua. While part of God's plan may be eventually to bring about the fullness of this reality for the entire nation in a very brief time, he offers this reality to us now.
The world appears to be more and more of a threatening place. Not that long ago if I would have told you that the day would come when you would not be allowed to bring a regular size of tube of toothpaste with you onto an airplane, you would have thought I was crazy. But that day is now here. Also, we are regularly told about the increasing possibility of the next great global epidemic. But by and large most people are oblivious to these emerging threats. We cope by ignoring these dangers and by distracting ourselves with work and the pursuit of pleasure. The day will come when we will no longer be able to ignore them. Our coping mechanisms will fail us.
But this is not "the heritage of the Lord" that Isaiah speaks of. There is a confidence and security available right now to those who welcome the power and presence of the Messiah into their lives. If we truly trust Yeshua, living life according to God's ways as laid out in his Word, we have nothing to fear.