Given the context of Psalm 58, the Reward for the Righteous there is a gruesome spectacle, “They shall bathe their feet in the blood of the wicked.” But it is an acknowledgement that God looks down and takes note of the works of the righteous and the works of wickedness, and then He acts. And when He acts, punishing the wicked and rewarding the righteous, the righteous rejoice.
Here we are at the Communion Table, the place where we remember the Lord’s death till He comes. It is also a place of a bloody spectacle but it is not the blood of the wicked but, rather, of the One righteous.
We do not rejoice here over the death of the wicked, unless our rejoicing is that our own wicked hearts are defeated by the victory of Jesus. We are washed in the blood of the One who died to set us free from sin and death. Our reward is forgiveness, peace with God, eternal life with our Lord Jesus, a reward of righteousness from the One Righteous. In this, we rejoice.