[quote=@Lewascan2]
I might just be spit-balling here, but what if... the reason her powers aren't quite as hilariously impressive as one might initially expect from a Mythic Grimoire is because said semi-sentient Grimoire isn't very happy about said budding god complex...? Hmmm.....

Questions for later.
[/quote]

[b]OOC Reason (and one that's most important on a meta level)[/b]: 
-Because playing a Saitama/Ainz/Superman in play-by-post roleplay isn't fun for anyone, including myself.

[b]IC Reason(s)[/b]: 
-We have established that Mythic grimoires aren't hilariously overpowered compared to the lower tiers. A single mythic can be overwhelmed by, let's say, 3 Legends (or 6 Fables) if the group knows what they're doing. [b]Wendil can CMIIW me on this though.[/b]

-In Lumi's CS, it's hinted that Sefirot is pretty much the one inducing the god complex as it embodies the concept of angels as a whole, not just the nice, polite messenger-types, but the good yet harsh warrior types too. Being selfless beings devoted to a singular purpose (protecting humanity from the Pageless), Sefirot accepts that some sacrifices to preserve the greater whole is inevitable and that sometimes violence is the best course of action. 

-Related to the previous point of angels being selfless, on the flipside, there's also Lucifer/Satan and his loyalists, which some people forget they're angels too and the Grimoire embodies [i]all[/i] angels. How this fact relates to Lumiere remains to be seen...