Zoro did it willfully, he stated that he was communicating his will(CoA) to his Blade.. So he was aware of his will.. He was completely oblivious to his other will(CoC), it's not his specialty.. You can't have control of something you're unaware, it was the same for Luffy.. People always act like CoC and CoA are similar, they are totally different.. Zoro didn't have CoA leaking out of him, CoA doesn't naturally leak out of someone, it would drain them physically.. CoC can leak out of unbeknownst to the user cause it doesn't drain the stamina, a whole other ability..