Mercenaries

Hansen's Roughriders

Tiger by the Tail

Though using appropriate camouflage in combat, for parades the Roughriders use a midnight blue with smoke highlights color scheme.

Per Mercenaries Supplemental, page 37.

Other references:
Pillager, FM: Mercenaries (plate 13)
Cestus, Mercenaries Supplemental (color plates)

Color Scheme
Insignia

Their insignia is a fanged and horned skull on a dun shield. Per FM: Mercenaries Supplemental, page 37.