If the adventurers are smart, they can solve this riddle and get the information they need.
To be used for the final encounter, find the final treasure, or anything that needs to be hidden away better then normal. Typical “who the heck would ever spend the time making it” but it is fun and a mental challenge for a change.
Then suddenly all your body paralizes and you hear a voice echoing in the distance "seems like another rat has been lured to my maze," this voice was terribly cold but playfull, "come on you are not already planning on leaving, the fun has only begun."
This magic greatsword has a minimal effect verses the unarmored but becomes more powerful vrs chain, then plate.Monsters
are mostly considered hide but some like dragons would be plate