I told you I’d get back to you on this one – so far as I can determine from the very few legible letters, this is a siliqua of Gratian, 367-383 AD, the obverse legend should be [D N] GRATIA[NVS P F AVG]. The reverse type is VRBS ROMA with Roma enthroned left holding Victory. The mint mark is fairly unclear, but I think it may be AQP[S] for the mint at Aquilea.
Having two holes would tend to indicate that this piece needed to be “fixed” in its position, but the orientation of neither the obverse nor reverse seems to have been of importance. The holes are pretty large and silver coins were used a lot less often for this, but coins so holed could be sewn to a leather jerkin for a bit of DIY “scale” armor. Or perhaps it was part of a bit of jewelry of some sort which needed to attach at two points as part of a necklace or bracelet.

 

Mark