I only need one. But first, I need to arm myself with a quote from Sailor Cosmos herself, and put the feat into context.
In the world of Codex Alera, people are able to manipulate the elements. However, these give them additional abilities. Earthcrafters can make people horny, metalcrafters can suppress pain and memories. Most of them are irrelevent here. However, watercrafters are highly empathic, and firecrafters can increase fear.
Now for the quote.
My feat is Gaius Sextus using firecrafting to make an entire army of 6,000 non-cowardly people do one of two things. Piss themselves and run away, and piss themselves and die of sheer fright. The former would count as incapacitation as their fear (and newfound geographical location) makes them unable to fight. The latter is obvious.
Sailor Cosmos is a coward, Sextus would be able to sense that as he is a powerful watercrafter and he uses his immense firecrafting powers to exploit that. If he can kill or incapacitate 6,000 people at once via fear, imagine what he'd do to one cowardly girl in a sailor suit.