Note that just having the mastery isnt enough you'll then have to petition the Dark Assembly with the appropriate bill to be able to create them.

Unlockable	How to unlock
Archer	Have someone with a level 5 bow mastery
Beast Tamer	Successfully capture a monster
Chaos Soldier	Finish the game once
Druid	Perform a 500+ Geo Combo
Female Ninja	Have someone with a level 5 fist and staff mastery
Gunner	Have someone with a level 5 gun mastery
Heavy Knight	Have someone with a level 3 spear mastery
Magic Knight	Have someone with a level 3 sword and staff mastery
Male Ninja	Have someone with a level 5 fist and sword mastery
Samurai	Have someone with a level 5 sword mastery
Sinner	Someone in your party becomes a criminal