IC XC NIKA (JesuS CHristuS NIKA)

[Valentinian]

This coin has IC XC NIKA in small letters either side of the head of Christ. The Byzantines had no "J" and used "I" and the "C" is a lunate "S". "X" is chi, our CH. This is  "JesuS CHristuS NIKA" which means "Jesus Christ Conquers". This is a common legend on late Byzantine coin reverses and the "IC XC" part is very common on obverses, too. It is less common to see the "NIKA" part on obverses, but here is a recent purchase with it.

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Romanus IV, 1068 - 1071. 
Romanus IV is most famous for losing the disastrous Battle of Manzikert in 1071. It greatly weakened the empire by ceding to the Seljuq Turks the east and the central plateau of modern Turkey. (More about Romanus IV below.)
Sear 1866
30-27 mm. 8.41 grams. 6:00 die-axis as is usual for late Byzantine AE. 
Pitch black.
Obverse: IC XC / NI KA (with bars above which mean they are abbreviations) either side of the bust of Christ. The coin has the same facing bust of Christ found on anonymous folles.
Reverse: Square cross with X in center and large pellets at the ends,
C  R  ["C" is a lunate "S". "R" is an epigraphical form of "B"]  ΣΤAYΡЄ BOHΘЄI "O Cross, help" [the "R" is deformed by the overstrike on anonymous Class H or I-- you can see traces of the undertype's reverse floral ornament with its bottom at 12:30 and a bit of the design around the "C"] 
P   Δ in the quadrants of a cross (with an X at the center) for
"Romanus Despot/emperor"   RΩMANΩ  ΔЄCΠOTH

So the reverse legend greatly abbreviates
"O cross help Romanus emperor" or "May the cross help Romanus, emperor."

as translated on this page:  http://augustuscoins.com/ed/Byz/legends.html

which translates Byzantine-coin legends.   

When Romanus IV lost the Battle of Manzikert he was captured by the Seljuq sultan Arp Arslan, who, after obtaining significant concessions, released Romanus to go home. It was a master stroke, splitting the Byzantines into opposing camps. The remains of the army had promoted Michael VII, Ducas--the proper heir, the son of Constantine X , to emperor not long after the battle. When Romanus was unexpectedly released and returned to Constantinople he found it already had a new emperor. Constantinople was in possession of the Ducas family of Constantine X and his young son Michael VII who was really under the control of his advisor Psellus who wrote the extant book Fourteen Byzantine Rulers. (The book is an inexpensive Penguin Classic paperback, as low as $1.64 plus shipping on Amazon).  Romanus lost his bid to reclaim the throne, was blinded, and sent to a monastery in 1078.

Byzantine AE is rarely in top condition, but it has great stories!

Show us a Byzantine coin with "IC XC NIKA"!
 

[Simon]

Okay, the verdict is out if this coin is an imitation or a new type. I lean to it being an imitation, but the weight and quality do support it being a new type. It is a Manuel tetarteron, and it does have IC XC and NIKA beneath. Bellow it, is a very nice normal example.   

[Simon]

Great link page with the abbreviations @Valentinian. Thank you adding that 

[Hrefn]

Here is Romanus IV in happier days with his beautiful wife, Eudokia, who was the widow of Constantine X.  

And here is IhSUS XRISTUS NICA on a miliaresion of Basil 867-886 AD

A little Tari of Norman Sicily.  Roger II 1130-1154 AD.  Palermo mint.  Obverse shows a Kufic legend;  reverse features a long cross with legend IC KC NI KA.  Spahr 63

And last a multiple Tari of Frederic II

[Simon]

One more, same as the OP. Really nice grade example.