Thanks for your interest.
Here are some more edge views. The last shot is a close-up of the
reverse and what looks to me like a small die break above the "E" . I think the coin must have been struck.
AS for the odd shape and
weight. I guess it could have been cut down for
jewelry but I can't see any definite signs like attachment marks. However the upper edge (top of the
head) is smooth while the bottom edge is rougher. Could be the way it was made or possibly filed to make a particular shape. The
flan is overall thin compared to most tetradrachms I have seen and this accounts for the light
weight.
I might also amend my description of the
portrait style from "weird" to "expressionistic". This trend away from the classical is seen in late tetradrachms from various places.