Coin from 337 AD, Constantinople mint. SPES PVBLICA across field, labarum, with three medallions on drapery and crowned by a christogram, spearing serpent. CONS in exergue.
Greek λάβαρον
A military standard used by Roman Emperor Constantine that displayed the ☧ symbol of Christ, which is formed by Chi (χ) and Rho (ρ), the first two Greek letters of the word Krestos ΧΡΙΣΤΟΣ or Χριστός.
Scholars have never found the etymology of the word labarum, but it is very obvious: the labarum is simply a display of a Labrys, the double-headed ax of the Earth-goddess taken from Hippolyta by Heracles, and carried by the kings of ancient times. The labrys is a vital symbol of the ancient mystery schools of Greece.
Labrys motif on a clay vessel from Psira, Eastern Crete. New Palace Period (LM I, 1700-1500 B.C.),