[WaT] Why is no one talking about ___?

Why is no one talking about how OPed Nightblood has become at the end of WaT. The damn thing can now grant surges AND use them himself. Not including the fact that he can apparently learn new types of Investiture. Seems to me, given enough time and opportunities, Nightblood could gain access to and perhaps even grant any type or magical power.

Imagine a Nightblood that can grant surges, access to the Dor, act as a metalmind for Fuerchemy and grant Alomancy like an unsealed metalmind. That would be wild.