Given you have a CI of 15 I assume you realise the shot is not perfect, but this is not an easy shot to take. I think there is enough natural light to not need the flash which is giving some off reflections and I would have moved in closer to concentrate on the central statue and cut the doorway on the left and the room on the right. Its not quite level so could be straightened. perhaps try to keep the top of the arch behind the statue which looks a little cut off. The colours in the water and behind the shadow have come out well. getting any detail on the statue is always going to be difficult with a black statue and the flash has helped a little, but caused a shadow behind which detracts from the statue itself. Without a tripod and some good lighting kit this was always going to be a very difficult picture to take well, and not one I could have done any better with.
Though nothing can bring back the hour
Of splendour in the grass, of glory in the flower;
We will grieve not, rather find
Strength in what remains behind;
I agree, tough shot. I thing I'd have experimented with bounce flash and portrait format. Maybe also try to fade the rust stains a little. Do you have any money left? :oD Thanks!