If you're playing fast and loose with other types of energy, Zoro's probably good to at least see shadows of. He has the use of haki, which is just strength of will, not magic and not even really spirit but he does use Observation Haki, meaning he could sense Illidan not only physically by location/proximity but feel his relative strength. So I guess Illi can pick up on that in reverse maybe? Otherwise he's totally a plain old normal human with monster-level strength.