Eye of Dullahan

[Namine]

Enchant deadly poison's poison status on normal attack isn't poison, but deadlly poison which counts as a different status, and the weapon element counts as a sub-element of "deadly poison" that's different from poison, and stackable with one of the main elements.

Which, this is a type of poison Luciola Vespa is also capable of casting since it EDPs itself. It makes it all the more confusing just which poison is at work here.