well, i couldn't find anything on the symbol, buuuuuuutttt...

using the theme of death, and the shape and design of the headpiece, i kind of figured somewhere in the middle east was the source for this one, include greco-romans. the symbol could be an infinity symbol, but i noticed little wings coming off the middle, almost emblematic of something cutting an object in half. combining that with the three gems present on the main skin brought me to one conculsion.

tl;dr my guess is "Atropos"