Cleaning a rusty khanjar without removing koftgari

[blue lander]

I assume this is a Syrian Khanjar but correct me if I'm wrong. I'm also assuming the decorations are koftgari and that they were done with silver.

As you can see, it's very very rusty and I'd like to clean it up a bit but without removing any of the koftgari. Obviously any kind of abrasive cleaning is out, but would soaking it in something mildly acidic remove some rust without damaging the silver? So far I've been using flitz polish and it's helped a little. I know it's going to be impossible to remove all the rust, but I would like to make it a little less ugly.

Weirdly enough, both the scabbard and the blade seem to have been chrome plated! Whoever made it scratched off the chrome plating on the bits where they applied the koftgari. It must have looked pretty strange even when it was new.