Board Thread:Suggestions forum/@comment-35321378-20190717061505/@comment-39689697-20190717160024

Thindithron the Great wrote: There's no Ironfist clan in the Lord of the Rings, so I'm not sure where the idea for that banner came from. There is a Dáin Ironfoot, but Ironfoot appears to be only his epithet, and not the name of a group of Dwarves.

I don't think it's likely that the Firebeards and Broadbeams will each get their own banner, since other than their names the two kindreds are virtually indistinguishable. http://www.tolkiengateway.net/wiki/Ironfists

This is where he probably got the idea from. Since the name Ironfists come from The Peoples of Middle-earth, "Of Dwarves and Men" by Christopher Tolkien, it may be considered secondary canon. Therefore, if no writing of J.R.R.Tolkien's officially describes something, The History of Middle-earth books are the highest source of authority. Don't quote me on where the names come from, as I don't actually own that book!