So, I think some Fighters Guild quests, possibly those of Baan Malur, should involve a plot of establishing Fighters Guild hall in Gnisis.
Why? Because there is no Fighters Guild hall in Gnisis and there is a book ingame that says there IS Fighters Guild hall in Gnisis. The book also mentions Erer Darothil who's master trainer of Illusion in game, so we can believe it's not work of a fiction.
Book is titled "Illusion" or "bookskill_illusion2" and here are some quotes.
“No,” said Silverthorn firmly. “I only have time to learn one spell. I have to kill Egroamaro, collect the award, and be back in Gnisis as quickly as possible. My wife worries when I'm away.”
His wife Liah was beside herself with worry. “All I could do night after night is toss and turn. I kept imagining you burned to ashes by that battlemage, and where would that leave me? Do we have enough gold that I could support myself if you, Saint Seryn let it not be so, were killed during one of these jaunts? I don't think so. Why couldn't you get a nice position at the Fighters Guild right here in town?
There would be some explanation how Fighters Guild hall in Gnisis got destroyed in fire or something and there is a need of rebuilding it, recruiting new members etc.