I like having the flavor that we have now. It's part of the setting and feel of the story.
Alhough directed at modern audiences, this is not a 'modern' novel. It's a story in of older style in a modern package. Keeping the Brythonic flavor keeps it true to the story and its setting. Likewise, R.V.'s very spare style serves this story well. Even when I suggest a change, I know that it might do damage.
Regarding Amy's suggestions above: I agree that those points could be changed, but in general I think her suggestions are too strong for the style. I could see Elen's last accusation being 'pleaded', since Camuir has a way of turning everyone's love into tragedy.
Regarding 'Onnen'--if the (back)story is essential, then it must be told sufficiently for the reader to understand. If 'Onnen' is part of the story, then she must be named. If the only thing the name does is amplify the tragedy, it is enough ... however ...
It might make sense to identify Onnen as 'your nurse' or 'her cousin' (or whatever) at first appearance, and only name her once, or only once in the story, and once in the reply (or in 'you cannnot blame'), so that she is identified as supporting dramatis personae here, but one with her own story. Ripples from a pebble someone tosses in a stream, the road goes ever on and on ...