Is this a coincidence?

[Adonalsium'sSpren]

did Vin swear the Second Ideal?

[+asmodeus]

Probably a case of something gestating in Brandon's mind.

A lot of details about the greater Cosmere, including the current minutia of magic in Stormlight, was still being worked out when he was writing and finishing up Mistborn. This is why we have some inconsistencies, like being able to push and pull on Atium, that are just... built into the Cosmere now.

[Master_Moridin he/him]

I honestly kinda figured it was a hint towards her deeper connection to Preservation.

[Ripheus23]

It's also not an unprecedented turn of phrase in general.