The Mastercutter's Dagger of [_______________]

These specialized daggers are extraordinarily excellent... for one thing only. Whether it be stone, or wood, or armor, they have a magical ability imbued in them at creation to a single type of inanimate material. When used on that one material they can cut through it like a hot knife through butter. Use them on any other type of material however, and they are worse than useless - they break! Longer versions (aka swords) have attempted to be made with the same magics, but they ultimately fail. No one is sure why. 

Benefit variations:

• They cut through the chosen type of material with no more effort than cutting through paper, or
• They do some multiplier of additional damage (such as 3x, 4x, etc) to the chosen material
• They cannot be broken by the chosen material

Limitation variations:

• Using them on any other type of material is like using a dull piece of metal, or
• Using them on any other type of material requires a roll on a 1d6 - on a roll of 1 they immediately break
• Using them on animate matter causes a shrill shrieking emanate from the blade and the wielder takes the same amount of damage (or takes the damage instead of the target)
• Material of the chosen type, if animated, causes the blade to respond the same as above

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