Opponent gains control of my {Sword of the animist} equipped creature and attacks me before I can unequip it. How gets the land?
you get the land.
You control the artifact so you get the effect. That said the wording is important. Because the sword says "when the creature attacks" the effect comes from the sword which you own.
If the sword read "equiped creature HAS, when it attacks search your library for a land" then the effect would come from te creature and he would have got it.
301.5d (http://imtgapp.com/forum/index.php?action=imtg;area=rule;number=301.5d): An Equipment's controller is separate from the equipped creature's controller; the two need not be the same. Changing control of the creature doesn't change control of the Equipment, and vice versa. Only the Equipment's controller can activate its abilities. However, if the Equipment grants an ability to the equipped creature (with "gains" or "has"), the equipped creature's controller is the only one who can activate that ability.
thanks dude!
Your welcome. 😄