Golden mail would definitely look cool.
I think the Berbers should have much darker skin too, and maybe be more inclined to wear white or black robes. I guess it depends on whether you want to predominantly represent them as being more akin to Maghrebi Arabs or proper Sub-Saharan Berbers (who weren't Arabs at all) -- I think the latter would be cooler, if only for a bit more variety on the basis that we already have four or five Arab culture groups. This was the period when Arabs and Berbers were beginning to assimilate (during the Almohad and Almoravid empires) so I suppose the distinction would become less obvious over time.
It's up to you of course, but I would definitely love to see that.