Most swords can be co-erced into staying relatively smaller thru rigorous pruning. Periodically remove the largest leaves by sliding a pair of scissors down the inside of the stem (this puts the blades point outward, helping make sure you only cut the stem you've selected) and cut the leaf off as close to the base as possible.
If you get too thick of growth, remove a greater number of leaves--choosing those both on the outside and inside of the mass. Obviously, this is also a great time to get rid of any damaged or algae edged leaves or any that have grown to a size or in a direction that obstructs part of the tank you want to be open swimming space.
In time, if growth is too vigorous, you can do a much harsher pruning by lifting the entire plant out and trimming off the largest, thickest roots and roughly 50% of the leaves before re-planting.