The Sword of Discernment

Praise the Lord! Sing to the Lord a new song, his praise in the assembly of the faithful.
Let Israel be glad in its Maker; let the children of Zion rejoice in their King.
Let them praise his Name with dancing, making melody to him with tambourine and lyre.
For the Lord takes pleasure in his people; he adorns the humble with victory.
Let the faithful exult in glory; let them sing for joy on their couches.
Let the high praises of God be in their throats and two-edged swords in their hands, to execute vengeance on the nations and punishment on the peoples, to bind their kings with fetters and their nobles with chains of iron, to execute on them the judgment decreed. This is glory for all his faithful ones. Praise the Lord!
Ps. 149 

Psalm 149 is a source of confusion and discouragement to many Christians. It's a beautiful psalm of praise and rejoicing for the first five-and-a-half verses. But from the second part of verse six on, things appear to get ugly. What began as a beautiful song of praise becomes an apparent bloodbath.

As I've had to remind myself elsewhere, psalms are prayers. And the psalmists often pray for things that never came about—at least not in the way the words would imply on the surface. In addition, some prayers are answered in the negative; and others might only be answered at the return of Christ—once again in ways that we cannot envision.

So I'd like to interpret Psalm 149 as a psalm for the day of Christ's return. And I'd like to think of the sword as metaphorical, the same way I read Matthew 10:34—
Do not think that I have come to bring peace to the earth; I have not come to bring peace, but a sword...
The sword, to my mind, is a metaphor for discernment. A verse that demonstrates this metaphor more explicitly is Hebrews 4:12—
The word of God is living and active, sharper than any two-edged sword, piercing until it divides soul from spirit, joints from marrow; it is able to judge the thoughts and intentions of the heart.
Clearly the writer of Hebrews was not speaking of physical violence, but of judging truth from falsehood. And since I do not believe Messiah in any way advocated bloodshed among family members, I'd like to think this is what Jesus intended as well.

And if it's true of Jesus and the writer of Hebrews, perhaps it's true of the psalmist here, near the very end of the psalter. Since no prayer contained in the psalms gives anyone license to enact the vengeance prayed for, and since we do not yet even know the "judgment decreed" in the final verse, it would be an utter waste of faith to interpret Psalm 149 literally. Enough that I pray for the proverbial sword of discernment that I might be among the faithful and not one of those being judged.

I want the spirit of praise, O Holy One, that I may express my joy for your sake, and not for a vindication of my own cause. For you are always right and just; I am all too often wrong. I pray this in the Name of him who taught me to pray.