Very nice! I found only two minor things that need to be "fixed", but they're only details.

[quote=TheBlueShotgun]
a raid into Brythonia
[/quote]

Brythonia is a Celtic Christian realm, which makes the Brythonians much closer to the other Celts rather than to the other Christians. Besides, the throne is held by the descendants of King Arthur, considered the savior of the southern Celts. Perhaps, the Pelagian kingdom of Dyfed would be a better target?

[quote=TheBlueShotgun]
Oden
[/quote]

I am fine with your char dissing on Christianity, but like most forms of paganism, Germanic/Saxon/Norse paganism is an ethnoreligion, which means that neither the Norse or the Saxons are going to try and force it on anyone as "the true faith". So, your character shouldn't have to worry about his people being forced to convert by pagan Norsemen or Saxons.