But thats pending if he feels like it, Oda has always let the "Swords have spirits" concept and lore be vague for him to play with. Its prolly why we dont know what Ashura is with Zoro.
Zoros whole arsenals of abilties is strange really, dude has that flying dragon technique, can paralyize people with fear, Demonic energy, etc.
Zoro just has alot of interesting and strange/supernatural abilties when you think about it.
and its left vague and blank for Oda to have fun with. Kinda like Franky and his cola, Nami and her weather powers, Usopp and pop greens etc.