I have found that dealing with factions while playing as the Byzantine Empire is almost trivial. Whenever one of my good for nothing vassals starts a faction against me, I simply revoke all of his duchies. I then give the duchies to either one of the counts in the de jure duchy or to one of my other dukes who has only one duchy. This has several advantages:
1. The new faction system causes vassals to almost never revolt when you try to revoke their titles.
2. No other vassals get mad at you when you revoke duchies as the Byzantine Empire.
3. Since the former duke is no longer a direct vassal, he can no longer join factions against you.
4. The new vassals who you give the duchies to will love you and thus will not join factions against you.
5. The disgruntled former duke will often rebel against the new duke, distracting both of them from yourself.
With this strategy, I have been able to maintain absolute crown authority and high taxes with ease. Just make sure no one forms kingdoms. This might require revoking duchies if anyone gets too much piety.
1. The new faction system causes vassals to almost never revolt when you try to revoke their titles.
2. No other vassals get mad at you when you revoke duchies as the Byzantine Empire.
3. Since the former duke is no longer a direct vassal, he can no longer join factions against you.
4. The new vassals who you give the duchies to will love you and thus will not join factions against you.
5. The disgruntled former duke will often rebel against the new duke, distracting both of them from yourself.
With this strategy, I have been able to maintain absolute crown authority and high taxes with ease. Just make sure no one forms kingdoms. This might require revoking duchies if anyone gets too much piety.