Talk: Episode XLIII: The Aku Infection/@comment-5366328-20170412042615/@comment-1108186-20170422210138

In Jack and the Zombies, it was revealed that in the hands of evil, the sword cannot harm the pure of heart, as you mentioned.  However, Aku was perfectly capable of using the sword to cleanly slice through massive stone grave markers and statues when he was chasing after Jack.  The time portal was destroyed by slicing up the rocks surrounding/supporting its material structure, based on what we saw in the episode--The sword does just fine slicing up inanimate objects like that, even in the hands of evil.