David is certainly angry in Psalm 58, primarily against rulers who are wicked, unjust and violent. Although this poem does not appear in the Lectionary, this feature alone makes it entirely relevant in today’s world as an expression of indignation and as a prayer for improvement in the rule of law and equity.
However, anger can lead to intemperate raging, often later regretted. David’s outburst, which he may or may not have later retracted, is the charge that the wicked are perverse from the womb. This is surely no more true of ‘the wicked’ than any human being. We all have our weaknesses but no one is thoroughly bad from the beginning. In the same mood, David desires that their fangs be pulled and worse, a sentiment we heard about way back in Psalm 3. Anger against evil is justified. But thank God for the balm of the New Commandment. The magnanimous interpretation is that David was really asking that the fangs to be extracted are those of wicked words and behaviour.
This and the next two psalms, 59 and 60, are all skips which continue the tirade against evil, its source and its perpetrators. Online and hard copy sources both classical and modern largely ignore these three psalms or treat them cursorily. If you want to sing this one, use a tone in a minor key, of which there are many in most books, and use Everett’s refrain in TEP based on verse 1:
Rulers what do you decree? Do you judge with equity?
Sixteen hundred years ago, Augustine in his commentary said of this first verse:
But hear ye the Psalm. “If truly therefore justice ye speak, judge right things, you sons of men.” Be it not a justice of lips, but also of deeds. For if you act otherwise than you speak, good things you speak, and ill you judge.