Sounds like some great coins @Voulgaroktonou ! I'm in the same boat, found Julian in the library but haven't read anything else of his.
I have more time than siliquae: My bull, also of Arles, illustrates that mint's unique addition of an eagle before the bull. I have never understood the thought process at the mint that gave us the great bull reverse on the AE1's and the decorative obverses on the AE3's but boring silver and gold types.
That's an interesting philosophical question @dougsmit - and it runs counter to normal 4th century practice. Was Julian tempted to use the larger flan coin (AE1) to trumpet his message? I'm also curious as to what you could buy with one of these large bronzes. I suppose we will never know.
Just picked another one of the type, this time Antioch. I'll show it when it arrives in the mail. Antioch is important because that's where Julian had a run-in with the populace.
Here's a new pic of my old worn JII bull coin, this thread finally motivated me to do it. Julian II, AE 1, 360-363 AD O: DN FLCL IVLIANVS PF AVG, R: SECVRITAS REIPVB, bull with stars above. CONSPA (palm branch) in ex. Constantinople mint. RIC VIII 164, 30 mm, 7.9 g.