The Mercenary Association was a giant entity, considered the most powerful organization made up of mostly commoners. Few nobles entered their ranks, as it was considered below their status. While that did not mean nobles never hunted, they simply had their own privileged organization.
Still, the top brass of the Mercenary Association was made up of members of all three powers, similar to the protection of churches. The reason for that was nothing more than to keep the commoners under control. Yes, a single noble could easily defeat multiple commoners, but if dozens of experienced fifth-step mercenaries engage a noble, then they would be able to put up a fight.
Dagger's Rock Island was small, so the Mercenary Association's branch mainly consisted of local commoners and lacked fluctuation of foreign mercenaries like in more populous locations. This did not only mean that there were fewer fifth-step warriors but also that their skills were lacking.