My guess is that she’s upset because it has been implied that Toivo has some sort of… connection… with Derrik/the beasts..? That he’s kinda keeping secret.
However, if I remember correctly she’s the chief of the guards or something, so she had a lot of manpower at her disposal, yet she chose to enter the lair of the beast, so to speak, with only three people… This had disaster written all over it (like, what else did they expect would happen, other than Derrik being there with a myriad beasts? It’s not like their aim was stealth, they just waltzed in). As the one who pressured them to do this and to do it in this fashion, I’d say she’s the one to blame. Also, it was kinda weird that instead of trying to figure out a way out herself, she bullied an injured teammate to do so.
Yet writing characters is hard, and I’m not writing a webcomic, so I’ll take it 😛 It’s fun!