On barding, I would think you need a more stylised, simpler rose, similar to the 'English Rose' used by the British Royals - see attached link:
http://www.historyonthenet.com/Tudors/wars_of_roses.htmThis should be fairly simple with GS - small, thin circle of GS 'dragged' toward the centre to make the petal shape, smalldiamonds for the leaf bits, and either build up the smaller petals with more, smaller circles or pre cut petal shapes. Alternatively scribe them into the original GS Circle.
The latter will keep it fairly thin as you do not want it looking too bulky.
Don't forget to look in the Library for your Knightly orders associated with Morr - The Knights of the Sacred Scythe, Black Guard of Morr and the two orders of the Black Rose could give some interesting modelling and painting opportunities and are associated with Stirland or witch hunting.