@Latarus Indeed. The dude's living in a delusion. But unfortunately I have the sneaking suspicion that the author will actually try to make this work. Watch as the MC manages to kill "the villain" due to his "mad archery skillz".
Unless they're filled with acid, those arrows r gonna do fuck all to a parasite. He could maybe catch one off guard while someone else is fighting them?
Giblow20 in the live action movie (which is pretty good considering some live action adaptations are bad) Migi transformed into a bow and shot Hideo Shimada with a pipe on his heart instead of Shinichi throwing a stone to him, so yeah a bow might be effective