User blog comment:Pacifista15/How much do they know?/@comment-4229874-20110804012434

C'mon, Zoro was trained by Mihawk, the greatest swordsman in the world. Mihawk might've told him of Haki or taught him Haki.

Ivankov might've said something to Sanji and considering Sanji's situation, he might've learned Haki himself.

You also forgot Robin, she knew of Haki too. Dragon might've told her too :P