These are usually lightweight executables that load your save file. They offer a user-friendly interface to adjust character stats and resources.
Before opening any editor, copy your original save file to a safe folder. If the editor corrupts the data or the game fails to load the modified file, you will need this backup to restore your progress.
A classic in the Koei Tecmo modding community, Van’s tools are known for their reliability in editing internal game parameters. How to Use a Save Editor Safely