I like the overall look of this cross. What bothers me is the different colour tone of silver on frames and on back plate. Cross frames are silver white, the backplate is more yellow - red. I would like to see it in hands, but if they had been made together, they should be of the same shade, both.
But I still tend to believe, this is veteran era repair (replacement), made by skilled jeweller. 300 euros is good price for such piece, I think.
Just my 5 eurocents.