I can't imagine Kobeni continuing her work in the agency. She didn't regain her wits even after stabbing Topknot-Aki. There's no way she could continue anymore. I guess it's off to the sex industry for her. I'd say Arai still might have a chance. He didn't become a total witless wreck yet, and in fact he only started breaking when things looked hopeless. Kobeni was pretty much broken from the beginning, not broken in a good way for that particular job (like Denji) but the worst way. She's pure dead weight, who actively endangers her colleagues. A transfer to a health delivery service or soapland is waiting for her.
A chainsaw's most crucial part is the looped chain, which is without an end or a beginning. I wonder if that's why the Eternity Devil is afraid of it, because there's some philosophical similarity. But then again, an eternity of pain is probably the more concrete reason, like Denji guessed.
Aside from all that, I guess only in Japan a superior would pressure an unwilling underling to start smoking. There can't be many developed countries left where smoking is still fashionable and favourable.