Unused Content/Ranked
Fire Diamond
"Fire Diamond" is a theoretical rank, made up by community members who wanted a rank beyond Diamond. While this idea has turned into something of a joke and never culminated into a real rank, a line of text in Brawlhalla's code references a Fire Diamond Loading Frame. This line of text is the only thing that exists; there is no art for the Loading Frame or reference to Fire Diamond as an actual rank.
It is unknown whether Fire Diamond was actually planned as a real rank (or at least as a Loading Frame), or if this is just leftovers of developers playing into the joke.
Unused Ranked Appearance
In older versions of the game, Ranked icons had a different appearance. These emblem designs did not last long, and were updated to the current banner designs in late 2015.
These designs were eventually re-used for the game's Steam badges.