Agree that some benefit would be appreciated ...
But i dislike when efefcts on me changes effects for artefacts ... i mean if this staff is supposed to poison me, then it should poison me no matter whatm i shouldnt be able to just turn it off, i should receive some benefit out of it ... if Hag's Eye would give me resistance to poison damage, to mitigate that effect, and some benefit (like temp. HP, or bonus damage) if i receive Poison damage, that would be cool. :3
I guess I think of it as something like the staff recognizing its own type of thing. As if the staff wouldn't hurt Auntie Ethel if she used it, but is cursed for anyone "outside" the family, so to speak.
But I would appreciate any benefit like that. Something flavorful that takes away a bit of the otherwise permanent sting.
Ethel gives you a charm which you can break to get an insane bonus, but I think it ends after the long rest.

Yeah, it's a consumable that goes away after a long rest. Meanwhile, the downside of Hag Eyed stays with you forever.