re: pruning
If you're pruning just because the plant is too big, usually you'd want to take off entire leaves, by cutting as close to the base as possible (the leaf stem will most likely just rot, not grow another leaf).
If you're pruning to try to stop decay, just cut off the decayed part of the leaf. As with any plant, the sharper a tool you can use, and the cleaner a cut, the less damage will be done.
edit: oh, and sort of unrelated, but I've found that amazon swords are like crypts, in the fact that they don't like to be moved. Try to pick a good spot at the beginning, and stick with it, if possible.