A basketball sized can that can diffuse up to a typical lightning bolt's worth of energy into gamma rays. In 100 words.
This ever-full, ever-surprising, ever-ridiculous flask contains a magical liquid that may be the best or worst thing you've ever drank. Handling with caution won't do you any good.
100 word magic item
The King always has the coolest form of transportation.
Combating any monster is often as simple as having the right tool for the job. The nightmarish lycanthrop is no exception.
These relatively plain silver rings allow the wearer to go unseen, unheard, and un-smelled and render the wearer completely intangible - but only to others who wear a Ring of Mutual Exclusion.
A longsword that lashes out in the hands of a graceful warrior.
The two gently-humming, crystal-studded blades are semi-transparent and sharpened to a deadly razor edge. The haft between the blades is decorated with brilliant multi-colored crystals. The balance and craftsmanship are perfect. You feel that these trusty blades will never fail you.
The ruling family depends on some magical artifact or place to secure their right to rule. A monarch isn't considered legitimate until he or she has been "accepted" by the artifact or place, whatever that might entail. It is also possible that some one else, not of the ruling family, could be accepted as the legitimate heir... A fact which the monarchs would like to keep secret.