Runes

Rune armor pieces are the most notable item in the game, along with its weapons. They are very rare, and only drop from monsters in Hell. All pieces require you to be of overall level 60 to wear.

The Rune Sword set requires you to wear the entire armor set + sword to be able to use it. It falls off if you unequip any of it at anytime.

The Rune Staff set requires you to wear the entire armor set + robe instead of plate to be able to use it. You can unequip everything but the robe to keep the staff on, but it will be unequippable if you take it off after that.