Hi, even without the shield being very visible you can look at other devices on the coin and compare them to existing examples and compare style, Here is an example of a bronze Demetrius Poliorcetes:
you can see that the helmet and plume are in a similar style, the helmet looks different one similar coins from Alexander III
You also have the same incription (ΒΑΣΙ), in the same place while most Alexander III inscriptions are in other places as far as I can tell...BA are often above the melm, beside, or DIRECTLY under.