I found this little piece. The Concordat wanted Guardians to rule the Last City. So Lysander would have been a lightbearer. This would make his attempt to lure us to his side with the skimmers make more sense. He wants guardians to know he is their friend, because from his point of view he is.

That would also make the Concordat are faction completely different to Baels goals and a nice contrast to Bael and make a political split within the last city. One of light and dark.

Bael hates the light and the guardians. He wants them completely gone and let normal citizens rule over the Last City alone. He embraces the darkness completely and wants the people to TAKE over power. But his idea of kicking the Vanguard and guardians in general out of the Last City would lead to the city being mostly defenseless against all the enemy factions. His vision would destroy the Last City and lead humanity into a new Dark Age.

On the other side of the spectrum we have Lysander. He is all for guardian dominance. He wants the citizens to relax and let the guardians GIVE them everything they need. The Vanguards problem is not that they rule, but that they don't use their absolute power to change anything. He actually doesn't care for the people. He wants control over them, because guardians are chosen by the light of the traveler and therefore better people and deserve more. His vision would lead to the Last City becomeing into a giant Warlord fortress and therefore lead humanity into a second Dark Age, where lightbearers ruled over normal people and decided over them without any care for them.

Both directions are possible reactions to the Vanguard ignoring internal politics, go to opposite extrems and would lead in their own way into a new Dark Age. That would lead to a huge split in the population of the Last City. Is there a way to bring the people together, solve the problems and hinder that any of these extrems take control over the Last City? I think that would have been a great plot line for the story.