I wouldn't touch it - these dresses were never meant to get wet - the black velvet ribbon will mat, unless its satin, in which case that is where the dye will most likely run - and you will never get that fresh look back - it will always look like it was washed and ironed.
These days people no longer buy real dresses from this period to wear unless they are REALLY sturdy, as in linen or wool. Silk dresses are bought by collectors and smell doesn't matter as much. By all means air it out, if you can, but just disclose that is has an odor - I am guessing its probably a musty basement smell? or maybe a gasoliney smell from old dry cleaning fluid? It's a very colourful dress in great condition and the smell will dissipate - eventually.
However, there is one more thing you could try, especially if its a musty basement smell, turn the dress inside out, and spray with a fine mist of lysol making sure not to soak the material anywhere - maybe outside on a sunny day so the lysol dries quickly. That should help a lot.