Since it's a small tank, it most likely won't have any sophisticated lighting. I would suggest java fern, which grows best when tied to a rock, piece of wood, or ornament - the roots will eventually latch on.
I have a good-sized java fern in a 1 gallon betta tank, with only a tiny lightbulb, and it's growing very well.
Swords and corkscrew vals need a lot of lighting, and a lot of space. One amazon sword can completely overgrow a 5 gallon tank, and vals grow to be over 1 foot tall. Stick with java fern :)