"Let the high praises of God be in their throats and two-edged swords in their hands," - Psalms 149:6 ESV
Would you use a two edged knife in your kitchen? I likely wouldn't. Why?
If both sides of a knife are sharp you must exert all of the pressure to cut anything from from the handle. Most kitchen knifes have a sharp side and a blunt side so that you can use your palm on the blunt side and exert pressure when needed or rock the blade quickly up and down to dice tough vegetables. Even heavy cleavers weighed to make cutting easier have a blunt back.
Two-edged swords must be extremely sharp and can only be controlled from the hilt. They can not be used to block because in order to block there must be a blunt back resting on some body part to absorb the blow.
"In his right hand he held seven stars, from his mouth came a sharp two-edged sword, and his face was like the sun shining in full strength. When I saw him, I fell at his feet as though dead. But he laid his right hand on me, saying, 'Fear not, I am the first and the last, and the living one. I died, and behold I am alive forevermore, and I have the keys of Death and Hades.' " - Revelation 1:16-18 ESV
Jesus' words are like a two-edged sword. He does not leverage them. He just speaks them and they have cutting power. His person is irresistible. The writer fell down at his feet like any man would. No one will stand against him.
"Praise the LORD! Sing to the LORD a new song, his praise in the assembly of the godly! Let Israel be glad in his 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 salvation. Let the godly exult in glory; let them sing for joy on their beds. Let the high praises of God be in their throats and two-edged swords in their hands, to execute vengeance on the nations and punishments on the peoples, to bind their kings with chains and their nobles with fetters of iron, to execute on them the judgment written! This is honor for all his godly ones. Praise the LORD!" - Psalms 149:1-9 ESV
Our life of praise as we walk in grace is a two-edged sword. It speaks for itself. We don't have to leverage it with the palm of our hands. It is dangerous to try because we will cut ourselves. Grace is not a cleaver or a saw. Nor is it a defensive weapon. We block with our shield of faith. Faith can rest upon our body and absorb the forceful blows of the enemy. Our sword will only get dull if we block with it.
"For the word of God is living and active, sharper than any two-edged sword, piercing to the division of soul and of spirit, of joints and of marrow, and discerning the thoughts and intentions of the heart." - Hebrews 4:12 ESV
Notice that the verse doesn't say that the Bible is a two-edged sword... It says it is sharper than one and a two-edged sword must be very sharp indeed in order to be effective.
What words do we hold in our hands and what words proceed from our mouths? Are they grace words? Because grace needs no leverage from us. Those words go forth and do what they were meant to do.
We don't want words that hack and saw at issues wearing us down with all the effort we have to put forth. We want words that reveal the irresistible Christ. Words that have supernatural sharpness. Words that cut through cleanly and decisively. Words that cut away what needs to be discarded and dices up the rest for easy consumption.