I had mistakenly believed that the guy on the cover of the GM Toolkit was Lazarus. Apparently it was not the case. The same picture is labelled "Ophiucos, Lord of the Infinite Swords" in Dominus Exxet but it's not entirely clear if it's referring to the technique being employed or whether the dude being portrayed is also called that?
So I was wondering if anyone could shed some light on that dude because honestly the high level setting character roster is a mess that seems impossible to understand without spending two months on google translated spanish forums.
(also Wen-M helpfully labelled the character artwork as

no. 1. Thanks Wen-M!)