It is not unusual for wizards to "stretch" their notions of morality. Through out history, even mages of upstanding character have demanded reality and nature bend to their wills by designing malicious spells and phemes. Wicked arts have also been used to enchant items, and these sinister practices flourished when wizards trained under the dastardly dragons. For this reason, you may encounter illegal items. Take them at your own risk!
Illegal items - or, within the context of the school proper, any items, that could irritate a teacher - require a certain amount of effort to achieve Concealment.
The higher the Concealability rating of an item, the more likely your possession will be discovered. If its Concealability rating is lower than or equal to your Finesse, the item may be safely hidden.
However, your instructors are well aware of these nefarious items. They won't tell you what magics spawned the dark creations, but they will confiscate your illegal items and severly reprimand you if they should find them on your person!
Concealability is a property of items, starting at "0" (where you don't have to worry about it) to much higher values, depending on the items Size and illegality.
To be able to hide an Item at all, its Concealabilty must be lower or equal to your Finesse Attribute.
The Concealability of Items add up. The total value of all items carried either on your body or in your knapsack must not exceed the value of 2 times your Finesse.
Items left in your wardrobe are totally safe there and do not add Concealability.
Some Spells, , and Items can influence the Concealability of an Item.