Well, it say "Target 1 face-up Equip <<Spell>> Card you control". Maybe thats why it cant be used on monster that equipped to Reli.
ok so I've tried using it on a number of different equip spells, in several occasions, but I can NEVER activate it, only set. What the heck?
I know it was working before on black pendant, but can't even activate it now even if I do control the dark pendant and opponent has some set s/t in s/t zone...