If I remember correctly, once they reach second stage profession, the name for each profession change. Like how warlock will become a summoner, magic archer should be the name for second stage archer profession I guess.

Perhaps they aren't really capable of using magic it's just their skills just seem magical so they call it that. Perhaps only Shen Yanxiao is a true magic archer. This is just a guess any way or if it truly is magic then it would explain why it's hard to reach because if the person has been training in dou chi all this time the they have start from scratch building magic power in their bodies which I imagine is possible it would just take a super long ass time

Since when he becomes an archer ahaha