I know that H in Greek is eta. My point was that S written as a Latin S is neither the C often used in Eastern icons, or the sigma used in inscriptions.
That said, others have made the point that since it can be either, why not consider it both. I’m okay with that, though I’m fairly sure that the usage was meant as ‘In hoc signo’ when it was put in.
I have only read Brown’s most famous book. If I picked the word up, it was from somewhere else. There’s no need to drive-by about it.
Doubtful given the ab initio signature use of the device by the JESUits.