I thought that this was how they would beat Aku in Season 5 of Samurai Jack.
It was hyped that the hieroglyphs were the only way to beat Bill. Then that failed and they got him through a mental possession/mind wipe combo. And in the same way, the sword was hyped as the only way to beat Aku. I thought the sword would fail and they would end up destroying him through some time paradox thing, but instead he just got back to the past.