Jury of Nine

Origin
After the downfall of the old tyrannical king, a guard named Xavier formed the Jury of Nine. It is also speculated that the Jury of Nine was likely formed to protect Lady Irene (needs verification). Whether the Jury Of Nine is still a thing as of season 2 is unknown.

Title
The way that the Jury members' titles work could be a number of things, including what weapon they use, what materials they use, their personality, or how they use their weapon. However, none of this is confirmed as being canon.

Powers/Abilities
Every member of the Jury has to leave their family in order to fulfill their duties. Also, members likely are given powerful armor and potentially weaponry as well so long as they are loyal. . Each member seems to have a special transformation form as well- we see Katelyn in her transformation in S1, Episode 100. As said above, the JO9 members are given armor and weapons in return for their loyalty, and not having that loyalty anymore would get your armor taken away (or killed if you are under Zane's rule). However, it seems that not having loyalty to O'Khasis anymore does not have a direct connection to a members powers and arsenal. An example would be Katelyn, who renounced her place in the Jury unofficially and kept the armor and her powers, until Zane took her powers away. The lord the member protects probably does the taking away of the arsenal and powers.
 * To be noted; The title 'Garroth the Diamond Soul' is fanon, rather than canon, and based on heavy implications and canon facts about personality, history, and weaponry.

Known members
Jeffory the Golden Heart (killed by Zane for helping Aphmau)

Katelyn the Fire Fist (Renounced, ally of Aphmau)

Garroth the Diamond Soul (Influenced by Zane, "traitor" to Aphmau)

Guards In Line For Jury
Since there are always 9 members of the Jury of Nine, guards who do exceptionally well during guard training will be put on a list. If a member of the Jury of Nine dies, renounces their own place in the Jury, or is relieved of their position for any reason, then the next guard prodigy on the list will take their place. It could also be that titles run in bloodlines, seeing as Abby (Jeffory's daughter) introduced herself as Abby the Golden Heart, though this could also just be because of some sort of honorary titling system.