>>89820450Jack's dad wasn't trained his entire life around the world for the sole purpose of destroying Aku, like
>>89821223 said
Aku is the only person who thinks that "Neither [the emperor] nor the sword has the power" to slay him forever, and "neither does [Jack]" and this is the exact arrogance that's going to get him killed. He gets BTFO so hard so often by Jack because he underestimates his opponent; he always has and always will because he cannot comprehend the things that keep Jack going when all the odds are against him.
Aku doesn't understand emotional and moral duty to other people. Aku doesn't understand selflessness. When he thinks he's going to lose, or if he thinks a fight is pointless, he gives up and stops trying, because he has nothing worth dying for and never wants to risk getting killed, or worse, locked up in a tree for eternity. Nothing is worth more to Aku than his own life, even if safety can get boring; the second he takes it for granted, he's done.
At the end of the day, all Aku knows is pain, and trying to avoid it as much as possible. The sword is significant because it can inflict pain on Aku by burning him away until nothing is left.
As much as I love Aku and hope he lives, the ending will obviously be his destruction and there's no reasonable way of getting around that.
