Repent; or else I will come unto thee quickly, and will fight against them with the sword of my mouth.
A B C read, 'Repent, therefore' х oun (G3767)]; 'Aleph (') h, Vulgate, Syriac, omit 'therefore.' Not only the Nicolaitanes, but all Pergamos, is called on to repent of not having hated the Nicolaitane teaching and practice. Contrast Acts 20:26.
I will come - I am come.
Fight against (war with) them - the Nicolaitanes primarily: including chastisement of the whole church at Pergamos: cf. "unto THEE."
With the sword of my mouth - from Revelation 1:16; but with an allusion to the angel of the Lord confronting with a drawn sword Balaam on his way to curse Israel: an earnest of the sword by which he and the seduced Israelites fell (Numbers 25:5; Numbers 31:8). The spiritual Balaamites are to be smitten with the Lord's spiritual sword, the word of His mouth (Isaiah 11:4).