Each Arbiter falls into one of four classes and is a certain type, depending on the Trait or Anthem they are correlated to. Arbiters also have different "speeds" at which they can be cast.
Ava and Bea skills can be cast in the same post they are invoked, while Cea and Dea skills must be readied with an Ava or Bea skill in a previous post.
Ava Class
These techniques represent foundational knowledge of being able to utilize Naten. Ava class Arbiters allow your character draw upon a deeper well of Naten to perform a task. Any form of hand seals, magic circles, runes, or special triggers necessary to do another technique in your arsenal falls into this category.
Ava must be used as preparation for Cea and Dea techniques, or to enhance the potency of a Bea technique.
Bea Class
These techniques are used with intent from the user. Arbiters in this class can be used freely in combat without the need to use an Ava skill beforehand.
Cea Class
These are techniques that require preparation to use; typically using Bea abilities enhanced or altered with Ava techniques.
Dea Class
These techniques also require preparation, but once activated are in use continuously. Techniques like areas of effect, summons, areas of effect and transformations fall into this class. Dea skills are special in that they can be used as conditions for more complex skills. , similar to the way that Ava class Arbiters work.
For examples of how to build your skills, check out these characters:
Zero Venkage
Ovan Hellgate
Kilik