The Empire has a set of runes that are widely used (but more common in some nations than others) - you can find info about them here:
You might also want to check out the Navarr Hearth Magic page:
The creation and tracing of complex designs has a magical resonance for the Navarr. At its most basic, it is found in the concept of map-making - of creating designs that mirror the world - and in journeys along paths and roads. A complex design represents a journey, but it can also represents the idea of permanence.
Wintermark styled runes on armour are rare and more often that not Navarri armour is decorated with intricate patterns of the Navarr thorns often tracing out their own journey through the Great Dance.
(This doesn’t mean you can’t use runes of course!)