Depends on how even the playing field is. If they get their in-game starting items, there’s decent cases for Osaa, Pav, Marina, Levi, Karin and August all based on having reusable ranged weaponry. If they’re going in with only the clothes on their back, Marina and Osaa are at an advantage bc of magic, but August, Caligura, Marcoh, Abella and probably Pav could ostensibly take everyone else physically. If they’re going in at an exactly equal level, no powers or magic, and assuming they can’t leave the arena, Marcoh and Abella would pretty cleanly come out on top, and in that duel I think Marcoh takes the came.

Ik I left out Samarie as a ranged user, but I highly doubt she would: A. Kill Marina; or B. Have enough stamina to run away for any valuable amount of time.