What makes a weapon magical?

Currently I’m taking a great workshop about writing fight scenes presented by Rayne Hall. The section about magical weapons was of particular interest to my fantasy writing. I enjoy creating detailed weaponry for my stories. I was glad to know I’d previously done a good job, but like to know what criteria to consider when crafting new ones.

She discussed what would make a magical weapon believable. Firstly, it cannot be invincible, no matter how much it is touted to be that way. A weapon that can kill without challenge is boring. Considering specifics, I’ve changed her points into my own after reflecting upon my best magical weaponry creations. I encourage you to take her online writing workshops. They are very worthwhile, and she is a seemingly untiring source of motivation.

Design:

* The weapon is made from a solid, natural material: stone, wood, or bone.

* It may contain a crystal, or a precious or semi-precious stone, because these are well known to store and enhance all sorts of mystical energies.

* It has an elongated shape, like a wand or a staff, so the magician may use it aggressively like a gun, pointing at a target to fire.

* It can be of any size, but are often tiny like a piece of jewelry, in order to be carried easily.

* There is often a religious connection to the weapon: aligned with a goddess, created by a god or monks, or blessed by holy men.

* It is ancient, passed through generations.

* It can only be bestowed as a gift, not purchased.

* The creation of the weapon involved a ritual or sacrifice. 

Operation:

* It is best to power a magical weapon through the skill of concentration. The magician must be trained, learn, and practice his/her ability to focus, even in battle. Mistakes lead to interesting plot twists.

* Injuries inflicted by a magical weapon may be invisible, which can provide interesting challenges for healers.

* Magical weapons often act slowly, producing affects hours or days later, when it may be too late to seek help.

* The weapon may affect the target's mind rather than his/her body.

* Many magical weapons can work on one of the four elements (earth, air, fire, water), essential qualities by which nature operates. For example, drying the stream as the affected takes a drink.

* The weapon can hit hidden targets, moving through or around obstacles.

Interesting complications:

* After being ritually charged, the weapon works only for a specific period, for so many days or until a certain lunar stage.

* The weapon may only work in the hands of certain people. I love Rayne’s examples for this: initiates of the order, male virgins, or post-menopausal crones. This can create interesting situations—if it works only in the hands of a male virgin, the enemy may send a seductress. I need to try that idea!

* Possibly the weapon works only if the user can hold a mental image of the target's face.

* The weapon may work only if the user is in an altered state of consciousness, like a trance. Hard to use in battle or while traveling!

Some of my most interesting magical weapons are paired or grouped, so they operate differently when separated from the mates, and are strengthened in the presence of the others. I particularly love the wandlore in the Harry Potter series. Each wand is of a unique combination (wood, core composition, length, and flexibility) to match perfectly with the personality of the witch or wizard.

Tell me about some of your favorite magical weapons.