It is three syllables and only requires one mouth to speak. [ Isn't that as much as one could ask for, in a name? He knows humans have had serious trouble interpreting his Enochian name over the millennia, especially compared to some of his luckier siblings, but 'Castiel' is the simplest they've managed to get while still staying close. ]

This is not something I have ever had to deal with before. How do you "deal" when you learn that everything you have ever believed may well be a lie?