Hmm, she was strong enough to throw a dragon in the previous chapter, and now she can't lift a human. The author sure is taking some liberties here.
If Berger knows slimes can control corpses, then I am also surprised that slimes being able to control corpses isn't common knowledge. You'd think people would be afraid of slimes wearing a person's corpse to infiltrate society. Or shadowy groups with monster tamers using slimes to replace people in positions of power.
there's something to be said about using a pinky-width bit of uncontained slime to hold onto someone from a position of poor leverage being less mechanically efficient than using said slime in a pressurized environment (saintess-magic reinforced human body) to drive her arms and legs like hydraulic pistons, i guess. she's laying on the ground with her arm dangling over a cliff, with no good way to move her body in order to use the strength of anything
but said arm, and said arm is currently half-empty because she shot a chunk of her, uh... self... out of it in order to reach him in time from that distance. and while said bit of self is prehensile, i imagine it's kinda like trying to lift weights using your tongue (just pretend that cherry-stem-tying ability equates to grip strength or something idk)- even if you can manage a bit of it, shit's still slippery and probably hurts. (though not as painful as having your blood vessels ripped out and used as ropes for someone to cling to - i believe i found & used the better comparison for the situation, but that's the first thing that popped in mind so i'm sharing lol, enjoy)
him being unsurprised about a slime taking over a human really is a big deal, though, i completely agree with that entire sentiment. i can only imagine it'll either be glossed over with his death or be handwaved ASAP as him having had some sort of divine revelation at some point which introduced the idea to him & told him only "certain extremely rare & special slimes" can do it or w/e & it's virtually unheard of as a result
also i think all this fretting over her being controlled is gonna end up as nothing, either he tries it (commands her to drop him or w/e) and fails bc of saintess-flesh serving as magical EMP hardening, or he's just too infatuated already to even dream of it in the first place