a castle key

Age has formed a layer of rust around the handle of this huge key. Relatively fresh scratches indicate the key has recently been used.

It is a castle key.
It weighs a couple of pounds.

You are thirsty.
You identify a castle key.
It is an unsellable key.
It weighs two pounds and three ounces, and it is worth about one celeb.
Its keywords are key, iron, and castle.