Lets try brainstorming special features for magic items. I like the idea of creating quirks and minor properties that are specific to certain kinds of magic items.
1. [Quirk – Tome] This magical tome must be fed at least once per day, or it does not open. Magical tomes like these can be more finicky than cats, and although they usually eat food, such tomes can consume just about anything. (Note: I once asked Ed Greenwood if there were tomes in Candlekeep that needed to be fed each day, to which he answered “Yes.” That would be an interesting job.)
2. [Quirk – Mirror] This magical mirror is punctilious as a majordomo. It requires the bearer (or owner) to observe the niceties of courtly etiquette when speaking to it, and to behave in a manner indicative of the bearer’s awe at the wisdom and sagely knowledge the mirror possesses. (Hat tip to Theodora Goss and her poem Sorceress in the Tower.)
3. [Quirk] Opinionated. This item speaks in single word sentences whenever its bearer does something particularly smart, dumb, impressive or lucky. The item is not intelligent, and when it speaks it is voiced by the DM, who determines the item’s base mood (friendly, taciturn, etc.) and tone of voice.
4. [Quirk] Unseen. Whenever this item is not worn or wielded, it blends in with its background. The last bearer of this item (or whomever is currently attuned to it) always feels a strong urge to look for the item and pick it up whenever they are not carrying or wielding the item–sort of like Frodo’s desire to keep possession of the One Ring, where that desire is on its lowest setting.
5. [Minor Property – Weapon] Tuning Fork. Whenever this magical weapon is struck by a solid object, all other weapons of the same type within 120′ give off an audible note for one round.
6. [Quirk] Bibliophile. This magical tome will not open unless its bearer reads out loud to the tome at least one whole page from a book that the tome has never heard before. The magical tome will accept material from chapbooks and broadsheets (such as The Hunting Horn of the Forest Kingdom from Cormyr, and The Coincradle Life from Amn).
7. [Quirk] Forge Compass. If carefully placed on the surface of a liquid, this item will orient itself in the direction of the place where it was crafted, and will float on the surface of the liquid for one round before sinking.
8. [Minor Property – Weapon] Dead Reckoning. When this item is made to touch any other weapon, this item will speak the name of the last 1d10 beings to have been slain by the touched weapon, at the rate of one name per round. This item does not reveal True Names. If a victim used more than one name, the item reveals only last name the victim used/was called by before they were slain.
9. [Minor Property] Brawler. Whenever the bearer is presented with an opportunity to start a brawl (i.e., not fight-to-the-death combat, though a brawl may well escalate in that direction), the item heightens the bearer’s urge to do so by drawing his or her attention to the closest person that looks like they could use a hard punch to the nose.
10. (Not sure if this should be a quirk or a property. Also need a better name.)
Substance Thief. This item’s texture and appearance changes to match the texture of the last substance it was made to come into contact with by its bearer. This does not effect the shape or magical properties or qualities of the item. The item does not change to match the substance of whatever is wielding the item (such as turning into calloused flesh to match the rough hands of a fighter, or becoming brown and smooth like the leather gloves worn by a rogue).
I like some of these. Definite candidates for my Cormyr sourcebook.