I don't know if BDO has a weekend vendor, but if it doesn't i think there should be. In destiny, warframe, and eso theres a vendor that comes on weekends and has stuff to sale. I think it could work in BDO.

https://www.blackdesertfoundry.com/daynight-vendors-guide/  here’s some information about it 

There’s the night vendor, you use energy to roll his inventory and you can get all sorts of stuff from hards to boss gear from him.