it can completely erase a character but its stated that there are world items specifically made for resurrecting players and they can counter it

but why do you ask? from what i know ainz doesnt have longinus pretty sure its not even in the new world at all

Essentially, I’m asking if a player with a World item would be immune to self erasure.

well i guess the short answer is no

There was a reference on the prolouge on how Ainz Ooal Gown conquered the Great Tomb of Nazarick. On one instance, a guildmate of Ainz commented that they could use 'Longinus' to defeat a certain world boss