I may be limiting myself too much, but so far I've been defining Weird West as fiction that takes place in 1800s America and incorporates supernatural/fantasy elements. That is to say, I haven't been including any Space Westerns. What defines supernatural/fantasy may be a bit broad, but whether something takes place in 1800s America has been pretty easy to determine.
So I was trying to think of any anime I've seen that might qualify as Weird West. And yet all I can think of are actually futuristic anime that happen to look Western. GUNxSWORD, Cannon Busters, and Trigun all look Western yet they all take place on some distant planet in the future. The closest thing I can find is Gun Frontier, which I'm pretty sure is just a straight-forward Western with no "Weird" elements (I haven't seen it).
Does anyone know of any Weird West anime? Or does all anime that takes place in a "Western" setting actually take place in the future? Given how much anime is out there, I have to assume some Weird West anime exists and I've just never heard of it.
There is an anime of Wild Arms. I had the first few episodes on DVD.