I have to start by saying both "wow" and "thank you"! People usually pay for this type of in-depth coaching!
I had been thinking about this game since I watched it so much creating the post, and like you, I think switch duelist was the opening play to make. Who cares if he uses 3 mana to take my 1 mana card?
Also, I completely missed his misplay going tall on vesper, but you're 100% right. Getting his other creatures out of trade range would have won him the game.
I didn't hide Marcella primarily because I would never have guessed he would trade it out. In fact, I was expecting to trade marcella the next turn to get skulkers to umber arrow. I was also expecting HBKs to drop (wasn't looking up his deck). But I suppose even then, pinging him for 1 hp really doesn't accomplish anything.
I'm much more comfortable with this deck when I draw my Armor Lurkers and big threats early and just go face. All the trading felt unnatural and threw me off my game plan. I appreciate seeing how you thought through the game, and also, I learned something important about playing light and having multiple threats outside easy removal range.
Of course, I hope you noticed I drew both shadow cats as my last freaking two cards of the game. lol.
Getting your Duelist levied kind of hurts actually since it's a two creature swing on board. Playing either duelist or looter is fine but the plan is to trade them, they're not great creatures to buff in this matchup.