I'm not an authenticator, but I can tell you that I find Etienne Aigner bags in second hand stores fairly often. They are usually priced in the $20 range.
Because of their low resale value, I can't imagine anyone bothering to fake them.
That said, I have found that the quality of these bags is very high, especially when you compare it to the price one pays for a used bag. They hold up extremely well compared to many other brands, the leather quality is good, and they can usually be polished up to look brand new.
Unless someone else has different thoughts, I don't think there is much monetary value (even on Ebay, the prices for this brand are fairly low and Ebay is full of price gougers), but the overall value of these bags is very high imo, because of their classic styling, durability, and leather quality.
Congrats on a beautiful bag!