He's fine, it just takes willpower to protect the group of them while pushing external violent spells. If he was using pure Chaos it would be harder too, Academic Magic is far simpler, which is why he uses the two of them interchangeably during combat. Istredd is still pointedly trying to ignore the shark eating openly, he knows he has a weak stomach, this is the worst time to get distracted by that.

Guiding the Ceknias toward Nanaue is a good game play because they are clearly cowed by him, losing their bravery to a superior predator. The Lunae guards learn from Claude and do the same thing, attack them so they spring to the side and end up in his vicinity. Istredd shoots fire from his hands but they too are to scare them into the shark man.

Eventually they smarten up. While the beasts rarely back off prey without a kill, they seem to understand how few are left and are scared off by the sharkman ripping them to bits. After some skitters and snaps on the outskirts, the remaining two (only two left!) Ceknias rushes off. If they have more of a herd farther away, it's unknown, but they have lost this battle.

The Lunae are relieved and the one from before goes back to focusing on the wheel. Istredd intentionally keeps his eyes off Nanue still, looking at Claude. "I'm pretty sure I said I'm never letting you hear the end of it."