Swords melt leafs all the time. Could just be that the leafs were emersed leafs are are melting because of that. One of my swords actually had the leafs rot off from the crown, and that plant is making a comeback now.
I would say that as long as the crown of the plant is firm and that there is even the smallest hint of new growth that the plant should be fine. But word of advice, while it is in this sort of state, put a ton of root tabs around it or have a really fertile substrate. I moved a small dying sword of mine from a tank with eco complete to a dirted tank and while it did nothing for months in the eco complete, it is taking off now in the dirted tank.