So apparently it’s possible to anchor citadels within range of i-hubs in faction warfare which presumably allows you to shoot at enemy ships with the citadels defenses as they try to bash the -hub. It’s unclear whether the citadel can shoot the i-hub itself to join in an attack.
This completely breaks a significant mechanic in faction warfare (i-hub bashing) and needs to be listed as an exploit by CCP asap, and fixed some time soon after that.
This is absolutely the best thing to happen in Fac War for so long. The whole mechanic is outdated and in serious need of some dev attention. Hopefully this will be the desperately needed catalyst for change.
Edit: Fix to be put in place in January, until then exploit notification has been issued.