What you can see on this screenshot is the inventory/equip/stats of my level 19 Guardian.
On the right side you can see three legendary items with a "no entry" sign or whatever it's called in the US. My character could theoretically use these items excpet that she doesn't meet the WILLPOWER requirements. Yes, items require stats to be worn and they will subtract from the stats as they are equipped. On the left side you can see the stats. The big white number is how much I have, the blue number is how much is used for equipment. As you can see, I clearly did not put enough points in willpower.
It just is by far my highest stat!
I also have 7 wisdom on one item and +4 all attributes on two other items. Yet I still can't equip THREE items I've had drop for me from bosses because my stats are lacking. I am wearing a GREEN shield because I don't have the stats for the blue one in the inventory. I am wearing level 4 legendary legs because I need the +4 all stats on them and couldn't equip the upgrade legendary legs in the inventory either. I'm wearing blue boots for the same reason and I am wearing a level 7 legendary helm because I can't upgrade to the one rotting in my inventory.
This is breaking the game for me. This is a retarded, arbitrary restriction that only frustrates and adds nothing to the game.