Grit (Ex)
A mysterious stranger is a force to be reckoned with. Instead of using her Wisdom to determine the number of grit points she gains at the start of each day, she uses Charisma. This ability works in all other ways like the Gunslinger’s grit class feature.
The maximum grit depends still on WIS while your daily recovery depends on CHA ? I pretty sure that the intent is that you change WIS to CHA for everything regarding grit but that is not written in the rules.