In the first version of the story, there was a full subplot about this key and how to prevent the Witcher to get it back, but it made no sense for him to hide it somewhere (he already saw what it did to give his soul o someone he trusted.)
So instead, I decided he was going to hang the key to his neck… And promptly forgot to draw it half the time.
So, I had to cobble an unsubtle revelation.
I swear I’m a pro !