While we're pointing out Karna stuff- while I should've pointed it out last time too, Archer's not scared really so much as dense as a pile of bricks about the whole thing. The awkward fumbling will come later, but for now he just plain doesn't realize that Hakuno has a crush on him and is starting to want to be more adventurous, so despite having his own feelings blossoming, combine that with his overwillingness to protect ze moe, he's just straight up not getting it.