As far as I know, artifacts are used in the offhand slot (sub-weapon). Some gives buffs when used for a period of time( i.e. 5kg dumbbell, ), and some can be used just for entertainment purposes(bubble stick).
What I would like to know is what were the other artifacts have you’ve seen in game and what it does, where could I get it?
I have also seen something like this before in a trailer doing some “wind skills” -> http://www.tosbase.com/database/items/630005/