Note: it looks like the two-edges of the sword refers to for and against the Pergamos ecclesia.
A. 12 And to the angel of the church in Pergamos write;
B. These things saith he which hath the sharp sword with two edges;
C. positive – 13 I know thy works, and where thou dwellest, even where Satan’s seat is: and thou holdest fast my name, and hast not denied my faith, even in those days wherein Antipas was my faithful martyr, who was slain among you, where Satan dwelleth.
C’. negative – 14 But I have a few things against thee, because thou hast there them that hold the doctrine of Balaam, who taught Balac to cast a stumblingblock before the children of Israel, to eat things sacrificed unto idols, and to commit fornication. 15 So hast thou also them that hold the doctrine of the Nicolaitans, which thing I hate.
B’. 16 Repent; or else I will come unto thee quickly, and will fight against them with the sword of my mouth.
A’. 17 He that hath an ear, let him hear what the Spirit saith unto the churches; To him that overcometh will I give to eat of the hidden manna, and will give him a white stone, and in the stone a new name written, which no man knoweth saving he that receiveth it.