I agree say trade between Muslims and Christians was secrete, discreet, or even uncomfortable is inaccurate.
It is much too small to have been a
horse decoration and there is no attachment for it to have been used as a decoration of any sort. It is a token.
I am not sure if the photo on the left is correct or upsided down. I do think it might be upside down and it might be a coat of arms.
The
type on the right
side photo
side (I can't say
reverse) could also be a crescent top of a
Roman standard (see the coins of
Philippi). I'm not saying it is, just that it is not necessarily
Islamic or a headdress of
Isis.