...hold on. Alongside Cailledh, Archives of Empire III lists four other 'lost Gods' of the Old Faith, the last of which is a nameless God of death that rules a 'watery otherworld' that serves as the afterlife. Water and the afterlife, that's Mathlann and Ereth Khial right there. But that's probably a concidence, as there's no connection to Eldrazor, Lord of Blades.
...the principal God of the Ostagoths was a nameless death God. The former territory of the Ostagoths is now Ostermark. The coat of arms of Ostermark is
a dragon holding
a blade.
perchance???