Hi Wolfie,
I well remember your visit to Malta and contributed to your post with the very same ' horse paperweight' pictured here in this thread.
Joseph Said sounds like a really lovely chap and you must have been thrilled to meet him and talk about Mdina.
He did describe them as ' horse paperweights' and not seahorses ....at least it clears that one up.
The Knight chess piece is essentially a horse....nothing more or less. If it is made of glass it can act as a paperweight ....obviously

I think this 'horse paperweight ' was initially based on a knight chess piece design as I mentioned above...an uncanny resemblance ( IMHO )
So mythfest or not I believe the design was inspired by a knight chess piece of the Staunton variety .
I've added some pics of another early example (with no neck what-so-ever

)
Have you spoken to Jim Munnelly about these to get his opinion of the design ?
Cheers Mike & thanks for all your research on the subject & thanks too, Rosie, for posting the subject !!