Hm, seance? There is a scene with Arthur and Merlin there in which Morgause is surrounded by all the candles and whatnot. I'm not entirely sure if it's actually the Isle of the Blessed or just a similar place, but creepy old castles do seem to be focuses of magic in these cases, so who knows...

Also, something on Arthur: it might also be conflicting for him because he hates magic. Even if he is slowly learning to view it in a new light, right now, he is against magic - and this could result in a bit of self-hatred if he learns that he is born of magic.

I'm actually not sure where Morgause is going to stand on this issue - in some cases of original legend, she's pro-Arthur, but other cases, she's against him. (In these cases, though, it's also usually Morgana who's actively against Arthur - we don't know where she is, yet, so this entirely up in the air. It would be nice, though - first "other" sorcerer that wasn't hellbent on killing everyone...)