It was the center one which gave me the clue as to what this selection could be. It is more than likely a Ægirshjálmr, the Helm of Awe or Helm of Terror in Seidr, Old Norse magic, and probably Icelandic. If so, it was a part of the magic called sjónhverfing, which was used to affect the mind with forgetfulness, delusion, illusion, fear, delusion or deceiving of the sight. It looks similar to this:
[I wanted to edit this and add more, but I kept getting an Internal Server Error from the edit page...]
What I wanted to say is that if these are not what I suggest, then I have no clue as to what they are.
They could be merely designs by local artists.
I notice that you are from Bankok, were you traveling?
Where and who did you get them from?
What metal are they made of?
Ah! Thank you, Adam.
I knew they looked familiar, but couldn't remember the source. I used to have Koch's book until I lent it to a friend (...who is no longer a friend!). I remember that his illustrations were good, but the corresponding text was sorely limited.