They're rather fierce, yeah. My lead squad got wiped out on the first map against the main boss fight but softened up the pests enough for the #2 squad to come in and wipe them out. The second stage was another story; I lost over half of my Knights (all five in the lead squad, everyone except Kerria in the #2 squad, everyone except Laurentia in the #4 squad).

It was admittedly kind of fun watching Kerria square off with the final boss pest and survive with ~20% HP though.