What does this mean (Yellow plus sign on weapon)

[Demon of Razgriz]

What does the yellow plus sign mean next to the Officers Chainsword name? I noticed some of my weapons have it, but I have no idea what it means and can't find anything on it.

https://steamcommunity.com/sharedfiles/filedetails/?id=3166213671

[limdu]

i think its just to note that its uncommon, as if named gear with different stats wasn't apparent, some items have yellow boarders to show this.