2004-12-01 : Heartseeker grants an ability to the equipped creature. The ability can target a creature with protection from artifacts (unless the equipped creature is an artifact creature).

2004-12-01 : The equipped creature’s controller chooses whether or not to activate the activated ability. It doesn’t matter who controls Heartseeker.

2004-12-01 : “Unattach Heartseeker” means just that — Heartseeker moves off the creature it was equipping and remains on the battlefield.