4 x 2 configuration is slightly non-standard but not necessarily uncommon. Depending on the stance and position you could even add two more buttons. As a DB blazer patch pockets can work. On a full suit I agree that you would want besom pockets or (maybe) flaps depending on what regional school of thought you belong to.
Anyway, you just described a basic navy DB blazer. Nothing too irregular about it. But the 4x2 config can be very hard to do justice to. Unless you are a real playboy then a DB also calls for a tie IMO.