I have to admit, I hadn’t given much thought to weather sealing when using adapted lenses. But then, when I’m using adapted lenses, I’m usually doing it in some comfort. Not everybody is.
There are definitely times when being able to adapt lenses in any weather conditions can be handy. Well, if you’re a Fuji X shooter with some Nikon F lenses, the Fringer NF-FX II (buy here) is the weather-sealed adapter you need (maybe).