While the gunslinger class in present playtest form is really all but unplayable, the thing I love the most is the feel and style of the class itself. That said, I will continue to hope that with other weapons revealed and some of the great feedback that's been given, the rest of the class will become more viable.
That said, on to my thought- and this is based solely off the dashing and bravado inherent in the Gunslinger as I see them - why about adding a deed that allows the Gunslinger to spend Grit to add to their Acrobatics, possibly also Sleight of Hand?
This could scale with level (+5 at First, +10 at 4th? Balance can be adjusted.), and maybe last for 1 action, or maybe last for X rounds, etc. It would basically just account for the Gunslinger 'manning up' and leaping into action in some crazed fashion- swinging from chandelier, sliding across the top of a bar, diving around a corner guns blazing, etc. Sleight of Hand could apply too, for things like juggling a pistol into the air while punching an enemy or throwing an improvised weapon at them, etc.
Certainly not overpowering, certainly not going to fix the current pains of the class, but for flavor, panache, and fun, I think this would be a great use of Grit at the right moment.