I'm designing a flesh-forged arm for my first character that has past honors and heraldry etched in and I was wondering if the city of Kraylorn in Lower Metsar had a set symbol?
When it comes to lore, what you see is largely all there is. There is no established heraldry for the moment. I'd go with Chris' suggestion.
As far as flesh-forging, I applaud the costuming, but bear in mind that there is no system for bodily augmentation yet. Thus, whatever you make is purely cosmetic. For it to count as armor, it has to function like armor worn by any other character, meaning it must be removable and transferable. This could change in the future, but for now, I can't approve of items that are theft-proof by design. ;)
While the city itself does not (from what I can tell), it is ruled over by the Bale Wardens. Since they have a lot to do with Istensia, I would imagine using her symbol (yellow sun surrounded by orange flames) would be fair. Praise the sun.
http://i1.kym-cdn.com/photos/images/newsfeed/000/282/817/2ee.jpg