It probably has been mentioned already, but lolwhocares
Hermode's Rod / Wand of Hermod. Okay, the song is nice and the concept is interesting, but... 1. it makes you unable to move; 2. it dispels everyone from your guild who goes through it; 3. it does not (or shouldn't, I believe) dispel enemies; 4. it prevents the use of skills; 5. the immunity to magic isn't worth all these downs most of the time; 6. it requires you to be near a portal (which, most of the time, is hard to get to, because you usually warp in way too far away from them).
It was only useful in eAthena 2 or 3 years ago, when it was basically a portable mass dispel that didn't let everyone who's not the user use any skills.