A previous post of mine showed some painted armour from the 15th century. Over at the excellent Bibliofind blog you can see various interesting examples of heraldry from a similar period. These range from the quite simple (i.e. in the image above) to the more ornate. They could perhaps be a source of inspiration for your group's Paladin, or those of various other knightly persuasions. Bibliofind has also collected other examples - check the links at the end of the blog post.