There isn't necessarily anything wrong with your amazon sword, but there are a few things that could be causing it to appear unhealthy. First, check to see if the leaves are receiving enough light. swords need at least 2-3 watts per gallon of full spectrum (6000-8000K) lighting. Another possibility is that the plant isn't getting enough nutrients. swords are heavy feeders and need a nutrient rich environment to thrive. Finally, check to see if the plant is getting enough water. swords like to have their roots immersed in water, so make sure the pot you're using has adequate drainage and that you're not over or under watering the plant.