[Morgeruat]

Moonblades according to Forgotten Realms mythology/cosmology are special intelligent weapons that follow a family line and choose their bearer, no one not of the line can use one, and they tend to either deactivate (become nonmagical temporarily) for unworthy users, or slay an unworthy owner outright (slaying is the typical resolution, with deactivation being a very uncommon one, typically if the bearer is the last in his/her line and the sword is waiting for the next generation before it reawakens)

They are of course an elf only weapon, I don't believe even half elves can be tapped by the blades for ownership. A fun, but not overly useful item, especially since a mage should never get into melee combat.