Arcane items are items which enhance a Wizard's magical powers in some fashion. Only a Wizard can carry an Arcane item and no character can carry more than one.
Scrolls are a type of Arcane item which contain powerful enchantments that enable Wizards to manipulate the power of magic. They are useful aids to spell casting and to resisting an enemy's spell. Only a Wizard can carry a scroll but, unlike other Arcane items, there is no limit on the number of scrolls a Wizard can carry, other than the total value of magic items he is permitted. Wizards can have one Arcane item as well as carry several scrolls.
As they are expendable items once a scroll is read, it crumbles to dust or its writing fades to nothing. A scroll can therefore only be used once during a whole battle.