Considering the conflicts between Wales, Scotland, and Denmark, I can see the border and maybe the coastal regions building up a strong martial tradition. Maybe one of the reforms of the later kings is creating new lordships over the borders to coordinate between the border shires. A March Earl, later becoming the etymology for Marshal? :-D
I assumed 'marshal' was purely a loan word from Norman-French. Turns out that is not the case... although the modern meaning has come from there its etymology does not. Given me more to think about.