matmaisan says:
I wonder if people not given authority by local nobility use insignia of this kind in Keoland? Maybe the Dungeon busters have a special status as a mercenary company?
Yes, the latter. Cecily is a bonafide HERO, and in her time was heaped with accolades and rewards. She has used that fame to get special dispensation from Niole Dra to operate adventurers in the region, and formed the guild known as "Dungeon Busters." Aside from the first few Dungeon Busters to arrive in Hochoch (who got by on the strength of Cecily's name alone), Olpert has been handling any questions of authority that may have arisen. You all have not needed to display any heraldry/insignia, because only town/regional officials would care about such things (and it makes conducting an incognito investigation rather difficult).