That's not a vine whip, that's a Thorn Chakram, a boomerang-like weapon.
Also, I'm happy that Terraria is apparently a thing in Japan, though I'm not surprised; like Minecraft, there isn't too much to translate.

Isn't thorn chakram counted as melee weapon? This girl is wearing early game mage set...

Also considering the thorn chakram I think is a mid-late game jungle item, I think that the girl's clothes are being used as a vanity set.

Or the artist just drew some designs they liked and game mechanics has nothing to do with it.