How do I get a key to the cabinet on the guard's screen?

Hint 1 of 6:

The blacksmith told you what you needed to do at the beginning of this
scene.  In case you don't remember, you need to get an imprint of the lock
and a piece of metal to make the key.

Hint 2 of 6:

How to get the imprint is described in the section of the guard's screen.
See that if you need more help getting it.

Hint 3 of 6:

Have you ever heard the line about turning swords into plowshares?

Hint 4 of 6:

Well, in this case, it might be better to turn swords into keys.