Verses with the word powerful in the New Testament (2 verses):

2 Corinthians 10:10
For his letters, say they, are weighty and powerful; but his bodily presence is weak, and his speech contemptible.

Hebrews 4:12
For the word of God is quick, and powerful, and sharper than any twoedged sword, piercing even to the dividing asunder of soul and spirit, and of the joints and marrow, and is a discerner of the thoughts and intents of the heart.