liz askew Mar 4, 2020:

I would get back to the client as this makes little sense.

philgoddard Mar 4, 2020:

It's probably a mistake for "l'asthénie". Sthénie means abnormal strength, though, as Emily says, it's obsolete. Asthénie means weakness.
I wonder if "protestataire" is a typo too.

Emily Gilby Mar 4, 2020:

It could be a typo but "sthénie" does exist in French and so does it's English translation "sthenia", however, the use of this word in English seems to be obsolete. It seems to be used more as an adjective in both English and French (sthenic/sthénique) but I can't find anything linking it to "protestataire"