J-
You might consider some small branches coming out into the dark area below the sword. Sort of the "roots" of of the plant/tree.
Also some rocks or horizontal wood etc would do well there.
I thought perhaps a staircase going upwards to the back of the tank would look cool. If you trimmed/pinched a few swords leaves, it could open up some room for light for some Xmas/Java moss to cover the rocks etc.
Without radically changing the tank, these are some ideas for you.
If you like that look, Crypt crispatula var balansae in that corner has nice leaves that are narrow and block less light. A group of them would make a replacement if you ever get tried of the sword.
Regards,
Tom Barr