"Bizarre?! I apparently have been yanked out of his own place and time and dropped into... whatever this is, confronting someone who looks exactly like my mortal enemy, and you have the gall to call me bizarre?" He was one of the least odd people he knew, as a matter of fact.
The repeated head bludgeonings were something Arthur could not argue, but they had no need to know that. Nor was he going to ask what a "dictionary" was, and thus provide them with more fodder.
The smile Katherine gave to Thor gave Arthur a pang. He was now convinced that this was certainly not Morgana, yet Katherine still looked like her... reminding him of when Morgana used to smile kindly. Before every expression she gave other than hatred was a mockery of the genuine caring and compassion she used to share.
Shoving the ache aside, he cleared his throat slightly to be able to ask, "So, what now?" If this was a situation that happened often, people suddenly appearing in this place, there was likely some protocol which was followed.