The fight itself is very mobilie for a tank so that does lower threat a bit, but he should still be doing just fine (as its not a rage limiting fight). So, make sure the tank isnt getting lazy on his rotation while trying to position ignis. Also, getting the tank to figure out the best way to reposition for scroch patches will help with threat uptime.
As far as yourself, the one thing I dont see listed is hand of salvation. Being a top caster DPS now, I have become a very close friend of HoSalv for fights like Hodir and General. Ignis is deffinitely a melee fight so get your pally(s) used to giving you HoSalv when you are out of tricks. Also, make sure the hunter continues to MD during the fight. This should help you push your DPS higher (as it would appear your threat capped).
I do find it funny that your GM and MT are telling you your DPS is to high though.... I would be so thankful for that problem from the sounds of it :P
I cast the spells that make the people fall over.