You can try it, but they generally need more than that wattage to grow. Now if, as was suggested above, you could put 4 of them over it, you'd be in business with just over 1.5 watts/gal. With CO2 your swords would do well. You'll probably need to use some root tabs in the substrate since you've elected not to use flourite or some other Iron rich substrate mixed with yours.
Swords are notorious for their root feeding.
Hey, let us know how you made out and what you eventually used, light-wise.
Len