OK, if you would like to only work with the pieces you have, then I would recommend pulling everything closer together so that it looks like it belongs together. So I would bring the lamp and chair closer to the fireplace and tucked into that corner. I would also bring the 2 crosses on the wall closer to each other and lower the one closest to the corner so that the top of it is even with the cross piece of the higher one. I would also recommend adding a few accessories to the top of the fireplace so that it adds some height and interest, but can easily be moved if necessary.

If you are willing to invest in this corner a bit, then I might recommend a taller, chunkier floor lamp so that it makes more of a statement. You might also want to add a small rug to define the area, thought this would depend on the rest of your room layout.

A few more pictures might be helpful, espeically one to see that whole wall beyond the fireplace.