In what mood is sebastien in the latter part of act 4 of twelfth night by shakesphere?

Answer 1

He thinks he may be pixilated. No, that does not mean digitally photographed. It is an old Celtic word for "magicked by pixies. " He is in a state of wonder because this beautiful and competent woman whom he has never seen before, Olivia, has professed her undying love for him, and even given him the gift of a pearl.

"This is the air" speech is the culmination of this predicament. She behaves oddly, but all of her servants obey her without question, so she can''t be mad.
In short, he's comfused but willing to go along. AHe must like what he sees because he agrees to marry Olivia the moment she suggests it.