This is false.

Firstly, Moenbryda wasn't killed by Nabriales; she died as a means to give her aether to power the artificial blade of light that Moen had been working on (shorn of the blessing, the auracite/aether-rod/Tupsimati combo was the only way you could reliably kick his ass for good).

Secondly, when Igeyohrm tries to kill you, she mentions that your blessing is the only thing keeping you alive - even if it is only at half strength.

I guess you weren't paying attention to the parts where you're relighting all your crystals that Midgardsormr went and turned off (albeit in a different order than you got them).