I have been looking for this functionality as well.
You could make an NPC Character Definition that has mele weapons as part of the skeletal mesh’s animation FBX file. Basically, the sword the enemy is holding is an actual bone that is apart of the NPC’s body.
There is something called a socket that is meant to attach items and props to various bones on the mesh of an actor but it seems to be completely bugged. Your NPC will have mele weapons in there hands but when you play the map in Fortnite, the weapons will be stuck to the origin of the NPC instead of the socket locations.
See this post. It has more information about this kind of problem