He came from Antioch and served under Constantius II and was probably appointed to ensure that nobody with western associations was serving in Britain during a time of mistrust, rebellion and suppression symbolised by the brutal acts of the imperial notary Paulus Catena.
This passage describes someone who came from Antioch and served under Constantius II, likely appointed to prevent individuals with Western connections from holding positions in Britain during a time of unrest, rebellion, and repression symbolized by the harsh actions of the imperial notary Paulus Catena.