Load an earlier save and grind a bit of exp. If you can't, you can always cheat...
Here's how to:
Go in the "data" folders and open either "weapons" or "armors" as txt files, then use ctrl+f to find the name of one piece of equipment your characters have. Then, find the line with numbers in brackets, and increase those numbers. You can get infinite stats this way, allowing you to oneshot enemies