It's a String Attribute, called "item name text override".
I know it's been stated in a previous thread that String Attributes aren't networked between the server and client, but this particular attribute seems interesting enough, though I'm not sure what it's used for. I think all it does is renames the new Australium Weapons, as those use Attributes on previously existing weapons to change some settings (#542, #2027 doesn't seem to do anything).
Any thoughts about this attribute? If what I'm assuming above is true, then either it's a "Weapon Prefix" thing or it renames the entire weapon. Not sure which.