It will not activate for certain Erasable debuffs, such as from the special moves used by Fomors outside Aht Urhgan. It also cannot remove Doom or Bard songs. It cannot remove the "Gradual Petrify" effect caused by Peistes; however, it can remove the effect after the player has become fully petrified.
The Eraser cannot be used while the puppet is disabled by a status effect, such as Sleep or Petrify. Thus, these effects can only be removed from the master. It can, however, remove Silence from itself. This is because attachments are classified as job abilities, not spells.
*Warning: The above information may or may not be accurate for Eden.