I'd interpret at least some of the stuff Harry comes up with as potions, rather than mundane stuff.
For example, when he "just happens" to have a holy water balloon to take on a blampire, that him succeeding in a lore roll to have the right kind of potion on hand. This also covers why Harry doesn't always have holy water on him, I'm sure Father Forthill would probably will willing to bless a super-soaker full on a pretty regular basis... Or when Kincaid gives him the paintball gun full of garlic (or whatever it was); easiest to implement as a potion again.
Of course, you run into a problem with mundane characters wanting to do the same sort of thing. If the ability is done rules wise as something they just happen to have and not a totally one-off event, then that's probably worth refresh, with maybe an effect total based on the characters contacts or resources or something. A techie character that pays a refresh point for the ability to just 'happen to have a" (cell phone, GPS, walkie-talkie, UV light emitter, business card copier, or whatever) is well within the rules space.