I wonder if that's final artwork? I know The Republic of Thieves had different artwork when it was first put on Amazon than when it was actually published. And to me it doesn't fit well with the rest of the series.
They might change it to something that looks more like the other covers in this series. Though I've noticed some changes in cover style preferences in the years between when ITKS and CM came out and now, so maybe the publisher decided to take a different approach? It would be nice if there were more of a style resemblance between covers. On the other hand, though, at least with this sort of cover there's no danger of anyone thinking, "Wait, is this scene even in the book? Is this meant to be a picture of that event in Chapter 6? If so, the artist got it all wrong! And why does poor Alaric look like a blond Justin Bieber?!".
On the other hand, while I can see the heraldic cover instantly catching the eye of long-term fans when the book hits the stores (since we'll be the ones to recognize those coats of arms immediately and know it's a Deryni book), I'm wondering if newcomers to KK's work will think "Nice clean cover design, what does the back blurb say?" or just "Meh. Boring"?