Derek Lowe's "Things I Won't Work With" entire series is both educational and highly amusing. This is another good article: https://www.science.org/content/blog-post/sand-won-t-save-yo...
"Layperson fire extinguishing: leave area and allow fuel to burn itself out"
"Professional fire extinguishing: leave area and allow fuel to burn itself out".
A small amount of hydrofluoric acid on the skin isn't that much worse than any other acid on the skin. It gives you a chemical burn and you certainly don't want any of this stuff near your eyes, but it is by no means instant death. We're not talking dimethylmercury or arsine gas levels of toxicity.
The problem with HF is that it penetrates tissues and eats calcium so you don't get the pain reception telling you how much HF you actually just got exposed to. That is REALLY DANGEROUS. You can have been exposed to a lot of HF vapor or liquid and not know.
Consequently, you have to treat every HF exposure as potentially lethal because:
1) you might have gotten a much bigger exposure than you think
2) HF consumes your calcium which can stop your heart long after your initial treatment if you don't replenish the calcium after a large exposure.
What happens is your body has to neutralize the acid that very freely absorbs into you through skin contact, and hours later when/if the amount you took exceeds your (mostly) kidney's ability to maintain pH/ion balances, your nerves stop firing for lack of calcium to enable the electrical activity and your heart stops beating normally, then at all.
I think part of the, hrm, atmosphere of terror surrounding it is the delayed onset of symptoms, in the rabies "by the time you can tell, you're in deep kaka" sense. That and its ability to just slide through a lot of protection.
Lol - that's the best