Found this at a Thrift Shop. Need help identifying it.

Bronze Jian ?

Thank you! I actually just found another similar one online after searching for so long. It was listed on an auction site as...
"AN ARCHAIC STYLE CHINESE SWORD AND SCABBARD
In the Warring States Period style, of modern production, having an antiqued bronze hilt and blade with inscribed Chinese characters with applied patination and verdigris, together with the conforming bronze mounted wood scabbard, in a shadowbox style frame.
Length of longer 43½ inches."  I thought I had a true gem here, but nevertheless it's a nice piece for décor!

To compare my thoughts with yours, point-by-point:

- I think the sword is quite long. The handle/blade ratio is such because it's a long two-handed grip. I don't think that the blade is short.
- Some antique bronze jian are in much better condition (including some Warring States jian, but also note that some were made quite late, as fake/replica antiques of the time, but are now old enough to be antiques in their own right). But to have this amount of corrosion on the blade and patina on the hilt fittings, and still have an intact wooden scabbard and grip would be rather surprising.
- A pierced pommel nut like that is modern; some old jian had open pommels and potentially tassels (I've seen Ming and Song examples).
- It certainly isn't a bronze jian blade geometry. Apart from fullers (the next point), a long ricasso like this is sometimes seen on late Qing or Republican jian.
- Narrow fullers like this aren't (normally) seen on bronze jian; two broad fullers are the most common (I've seen 3 narrow fullers, but near the hilt). I don't think they're too clear for an antique (but this depends on age/condition).
- I didn't look for similar guards on antiques; it's probably inspired by the wide jade guards on Han steel jian, but it isn't a close resemblance. Whether there are antiques that are similar, I don't know. I've seen similar on modern replicas/fakes.

But mostly, it's a steel blade. Red rust = steel or iron. They're not especially historical to my eye. Apart from not being very historical in style, it's certainly not in the style of an ancient Chinese sword (for the reasons you pointed out). However, it is similar to a whole bunch of modern Chinese swords. I'm not sure exactly what these replicas are meant to be imitating, whether they're inspired by bronze jian or steel jian.

So, we've clearly interpreted the photos differently (e.g., estimating size, bronze vs steel). Some of the differences above just follow from this. If the OP was to tell us the length, and whether it's iron/steel or bronze (or at least whether it's magnetic or not), then this would resolve some of these differences.