The fact he was using 6 inducements wasn't as shocking as seeing with their own eyes, a poison Elementalist uses Oxidation reaction as an inducement. They knew that rust wasn't actually that poisonous to humans if absorbed in small quantities. So why was it being used a poison?
This question was eating the VIP viewers' minds, not letting them focus on the rest of the battle.
What they may not know was that Felix's primogenitor bloodline allowed him to use poisons that affected every being and race in the universe! Not just the human race!
This meant Felix could use some inducements that were totally beneficial to humans, meanwhile deadly as an acid to other races!
The Iron Titan's current situation just further proved so, as it kept lying on the ground, having difficulty standing up after its limbs joints turned rusty. However, not standing up was one thing, and not defending its vital points was another.