Dwarves and the northern war of the rings

[Balin999]

It was a nazgul, it could only be one from the discription. It doesn't seem to match the timeline, though, does it?

Actually I'm not very sure about this. When Gloin tells his tale he cites the messenger who says "For Sauron knows" and "as a small token of your friendship Sauron asks this"
I can't remember any person being it a wraith or human in Sauron's service who was permitted to speak Sauron's name except The Mouth of Sauron. I think it is possible that the Mouth was sent to the dwarves, because the Nazgul were not rhetorical experts I think. And a real human would appear more trustful to the dwarves, if any servant of Sauron can appear trustful.