The Roman punishment of “decimation” was to make each ten-man team in an army murder one of their number (the whole team being killed if they refused).

Practically “Saw”, in real life.

crap i thought it meant 'skin alive'

It apparently does have continued use as an approximate synonym to chafe or flay when used in the appropriate context:

https://www.merriam-webster.com/dictionary/excoriate

https://www.collinsdictionary.com/dictionary/english/excoria...

That would be flaying. But in a medical context I think excoriating is skin removal... it's just not being used literally here.