That's the first time I encounter such a reverse on an LRB. For this reason I acquired it today. My first usual search didn't lead to a match, despite the fact that it was merely struck in Thessalonica to narrow the task. It weighs 2.57 g. and measures 16 mm. Also I managed to scan it at double size and maximum resolution. Thanks..
VIRTVS ROMANORVM centenionalis; Thessalonica, AD 379-83 RIC ix, p. 182, 42; LRBC II 1816; Sear 20135; Cohen 57
Nice coin of Gratian @7Calbrey - can't really make out the lettering on the reverse except for the second half of ROMANORVM. It's either VIRTVS or GLORIA as the prefix, I guess.
The interesting thing is that the (almost certainly) Greek-speaking celator seems to have used a lunate sigma instead of an S in VIRTVS, writing VIRTVC instead.
In RIC it is, but that has little correlation to how hard it is to find in the coin market or its value.
Gratian, AD 379-383 Roman Æ maiorina (Æ2); 22.6 mm, 5.87 gm, 8:00 Siscia, AD 378-383 Obv: D N GRATIA-NVS P F AVG, Diademed, draped and cuirassed bust, right Rev: REPARATIO REIPVB, Gratian standing front, head left, raising kneeling female on left, and holding Victory on a globe; in exergue, BSISC• Refs: RIC 26a4; LRBC 1519; Cohen 30; RCV 20008.
GRATIAN, 367-383. AE-Centenionalis (378/383), Siscia, Ob. D N GRATIA-NVS P F AVG diademed, draped and cuirassed bust r., Rev. CONCOR-DIA AVGGG enthroned Rome, facing, head l., holding globe and reversed spear,ASISC. RIC 27a.5, LRBC 1528.
or given that the others in the legend look fine, it is just the result of the way it was struck or maybe a clogged die or even patina obscuring that bit.
I only have these Au Gratian guys: RI Gratian 367-383 CE AE 17mm Reduced Folles Emp Stdg w Shield and XP banner labarum RI Gratian 367-383 CE AE 17mm Reduced Folles Concordia RI Gratian 367-383 CE AE 17mm Reduced Folles Leading captive XP banner labarum
You can look up late Roman AE types at http://augustuscoins.com/ed/ricix/ where the OP coin is Type 19.