I was thinking that, since this is an umbrella gun, it probably wouldn't make sense for it to have multiple pistol-sized bullets loaded, but rather 1 (potentially) rifle-sized bullet loaded. Taking that into consideration, I think these might be "decent" stats... idk- I'm throwing numbers at a wall rn.

(Numbers are based on stock revolver)

[] While active: Slows your decent while airborne. Cannot attack while descending.
[+] 35% damage bonus.
[+] 50% faster reload time.
[-] -85% clip size.
[-] Increase in push force taken from damage and airblast while active.

I feel that this is fair, but feel free to make adjustments at your disclosure

explanation:
The descending part seems self-explanatory, you fall slower while falling in the air, but you can't attack while doing so (since the barrel is pointing up)

The damage bonus puts it closer to the damage the Family Business, but concentrated into a single bullet instead of a spread, and this is because of the higher caliber of ammo that would be used compared to stock

Faster reload speed (from 1 sec to 0.5 sec) is because it's only a single bullet being loaded (I'd imagine that it slides into a slot somewhere, similar to a lever-action rifle?)

Clip size reduced to 1, since this wouldn't physically be able to hold more than one. (And Spy isn't crazy, unlike Soldier and his 4 rocket, one barrel shenanigans)

The increased push force is due to the fact that it's an umbrella, and now, it could JUST be from airblast, but Pyro already hard-counters spy in so many ways, it'd seem unfair to make this another Pyro-only related downside, so Soldier, Demoman, and Engineer can also launch the french man with increased effect.