@guy : Divide the Welsh society into free Welsh and Marchers is normal, it was like this … The Welsh Marcher lords were dressed mostly like English Norman nobles and maintained retainers. it’s normal, it was like that … But in the 11th and 12th century the free Welsh had kept all their celticity, that’s why the Uchelwyrs (with round shields please) have so many charms …
C11th certainly (though for example in what became Monmouthshire there were Anglo-Saxon intrusions (The Godwinsons built a hunting lodge in Portskewett burnt by Caradog ap Gruffydd in 1265 (Anglo-Saxon Chronicle). The connections with Anglo-Danish society (not always adversarial) must have influenced Welsh dress and military methods, after all Wales was no longer using late Roman styles and methods so there had already been change.
C12th – doubtful – already change through Marcher contact.
[and just a language point to us all – Uchelwr is the singular, Uchelwyr is the plural – no ‘S’ required. It just means ‘high man’ literally or ‘nobleman’ in idiomatic translation]