Kruber: Flail [With Shield]
A heavier version of the normal Flail, could also be a 2h variant. Bretonnian Grail Knight are also often depicted with them
Bardin: Doomseeker
Not really a flail but a semi-ranged weapon, exclusive to Slayer [only ever appeared on Slayer unit but never strictly forbidden for non-Slayer Dwarf
Kerillian: Whip or Beastmaster Spear [Additional Whip]
Elf don’t often use Chains weapon but some very sadistic Druchii have developed a way of using their tool of torture on the battlefield, 2 famous cases are the Sister of Slaughter and the Beastmaster Rakarth
Saltz: Sigmarite Flail/Comet Flail
Iconic variation of the Flail that Sigmarite uses, it’s a 2 [or more] headed 1 shaft Flail
Sienna: no real need for her to have one more [lorewise speaking]
As much as I like Flail I only see 2 of them as possible future weapon:
Sigmarite Flail for Saltzpyre, simply due to the fact that they are somewhat iconic and Kruber’s Flail [And Shield] due to the fact that there aren’t that many weapon for GK
Lastly, Censer Bearer Plague Monks