I would put like a jungle of val in the back behind the large piece of driftwood. On the driftwood put some java fern/moss or any type of moss. In the front of that A carpet of Crypt. The sword should be off center and fill in the rest of the space with a species of stem plant to contrast against the board leaves of the sword (Rotala, ludwigia, ect... ) and then in front of those, I would do a carpet of dwarf sag. The leaves size, shape and color would look great against the sword and stem plants.