Earlier, Isaiah had invoked an agricultural imagery of burned fields. While the fields that are burned are certainly destroyed, the end result is that nutrients are returned to the soil, and at a future time there will be another harvest. That imagery returns in verse 3. There is joy in the harvest. The idea is that there will come a time of abundance after the coming privation.
The yoke is the burden of foreign domination. Jehovah will remove that. The staff and rod are symbols of authority and power, respectively. Thus, both authority and power over the children of Israel will be removed. In the shorter historical future, this will remove Assyrian dominance. Then, it will remove Babylonian dominance. In the final days, when Jehovah takes his rightful place as king, it will remove power from all earthly powers and Jehovah will reign supreme.
The ultimate future salvation is referenced in verse 5. This will not be an earthly battle in which the warriors are steeped in blood, both their own and that of their enemies. It will be in the final times, when will come a burning of all the wicked prior to the installation of Jehovah as the king.