I think this is a great name for a wraith faction. It would be the kind of name that would arise from other species' description of the faction; they arrive unseen, silent, barely interacting with the material world, and can only be detected in the small disturbances they cause to the environemnt, like the rustling of papers and leaves. It has an an ominous vibe, too, of a largely invisible presence the certainty of which is always in question.

A faction named after their rustling, whooshing and creaking sounds among branches or metal corridors is very evocative of stealth.

Furthermore, it allows for the faction to have a name that is both plural (The Rustling - a descriptor for all of them) as well as singular (a rustling). In the singular form, the -ling suffix works really well, as it brings to mind words like changeling or halfling, and has thus this "vaguely defined non-humanoid creature'' feeling to it.

"Rustling'' also contains (though is it unrelated to) the word "rust'', which means that in its singular form, a rustling, it can also be interpreted as an aged, worn out creature, something ancient and metaphorically rusted, which fits well with the fact that this faction is meant to be very old.

Lastly, with a lot of names of factions in game being actual proper names, inspired by words perhaps but not directly meaning anything (Vodyani, Lumeris, Horatio etc), or names that a faction has chosen for itself (Unfallen, United Empire), it would be nice to have a name that is more of a direct descriptor of what this faction is perceived as; some sort of insidious natural catastrophy.