As expected, the intrepid researchers turned up some gems: a heart-shaped music text, a fleur-de-lis shaped text, some early-period constellation figures.
It was the dragon shaped figure though that inspired me. This is a 14th c Hebrew manuscript from the BL (Oriental 2733 f50v)
This is my English-text interpretation, to serve as Dom Duarte's Silver Guard.
It struck me that he can now 'bear the badge of the Order' and I thought this was a cool way to convey that honour. TRM's signatures would serve as the final fill in the hind leg!
It took a couple of practice tries to get the length of text right, and the inter-line spacing, and I didn't worry about breaking up words to fit the space.
The Hebrew text has an advantage of not having ascenders or descenders, so the lines are extremely regular, providing a sort of texture to the figure. I had to add some texture here and there with flourishes to fill out the figure. I suspect some of the Hebrew characters are filler flourishes in the dragon's feet and tail.
Robert pointed out that this dragon doesn't have wings, and is a bit dog-like. I hope the long tail and teeth, and the long ears convey enough dragon-ish-ness. There's some variation in the species, I understand. :-)