Our example is by Valentinian I from the mint of Siscia catalogued RIC 14a page 146 expanded to series xxx (page 143)

Obverse: DN VALENTINI - ANVS PF AVG - draped and cuirassed bust right with pearl diadem

DN = Dominus Noster (Our Lord)

PF = Pius Felix (Pious and Happy in a sense of 'blessed' more than 'jolly')

AVG = Augustus (Emperor) Note the break in the legend honors his position of a senior Augustus.

The drapery on the bust is secured by a large clasp on the shoulder below which we see a trace of the shoulder armor of the cuirass.

Reverse: GLORIA RO - MANORVM (Glory of the Romans) around edge; BSISCV mintmark in exergue; Q A and a fancy 'k' symbol in field - soldier holding Labarum dragging captive by hair

'Labarum' is the term for a standard bearing the Christian symbol Chi-Rho. This type is the most commonly available Roman coin that shows this symbol.

There is more about the reverse that is not known than there is that we can explain. SISC identifies the mint at Siscia. The B identifies the workshop within the mint that made the coin. In this case, shop B (Greek numeral for 2) seems to have worked for Valentinian as did shop G (3) while A (1) belonged to Valens and D (4) to Gratian. Roman mints were not consistent on how the shops were divided between the rulers. In other cases, all shops struck for all the current rulers.

This issue seems to date to the early period after Gratian was elevated to power (367-375 AD). Specialists have identified a large variety in letter/symbol combinations in the reverse field but I am unaware of anyone having deciphered the meaning of these letters. Equally mysterious is the letter 'V' following the mint mark. Certain letters appear in this position for certain rulers but the 'code' is not understood. There remains a great deal of opportunity for the next generation of numismatic scholars.

Our example portrays Honorius, emperor of the Western part of the Empire following its division on the death of his father Theodosius I. Honorius never actually ruled (there is some evidence that he was somewhat mentally challenged) but was the puppet of the powerful advisor Stilichio. Few Western Emperors of the Fifth Century had much to do with actual rule but served as Orthodox puppets for the German strongmen whose Arrian beliefs made them politically unacceptable to bear the title of Emperor themselves. Honorius is shown wearing a pearl diadem. A star is always shown behind the bust but the significance of it is not clear.

DN HONORI - VS PF AVG (see #11 for translations) The split legend honors him as the supreme ruler of his part of the Empire.

Reverse GLORI - A ROMA - NORVM (Glory of the Romans) surrounds three standing figures of the Emperors. Honorius is on the right and looks at his colleagues Arcadius and Theodosius II who ruled the Eastern Empire. Theodosius II was made Emperor by his father Arcadius when he was about one year old but he was probably a bit over five when this coin was produced (406-408 AD). He is usually shown shorter than the other two.

The mintmark reads ANT D (4) placing the coin at the Antioch mint's 4th workshop.

The coin catalogues RIC 153, volume X page 252. This is believed to be the last coin type of Arcadius before his death in 408 leaving the Empire to his seven year old son who was assisted by advisors including his sister and later his wife. Even though the coin was struck in the East, some were made to honor the Western Emperor Honorius. These little coins often have small flans making it hard to read the legend and identify the ruler. This one is pretty clear, as these go.