<div style='font: 14pt "Sans Serif"; text-align: justify; padding: 0% 15% 0% 15%; '>When I saw the movie again(and again...), on the way to protecting Inuyasha's mom, his Dad tells Myoga warns him that he needed to rest from his battle with Ryuukotsusei, but Inuyasha's father says something like "It doesn't matter, I don't have much longer anyway." OK, at this point, this could mean that (a)Dad's wounds were so grave, he was going to die anyway or (b)He knew something else.
Later in the movie during the fight in the castle as it burned, we saw Dad take care of Takemaru (the dude who killed Inuyasha's mom) in like one sword stroke on a dead run. It was like Takemaru was an annoying fly. And notice right before they cut away from the fight on the castle, you see Dad use that special technique from Soongu. But then you see nothing. OK, so now we're to believe that this pathetic human ("insignificant man" in Sesshomaru's words) beat Innuyasha's dad, some sort of Demon lord, in a fight with one arm? And I know there was fire and all, but fire is supposed to kill this dude? Right.
Also, later in the movie Soongu says that Dad was a fool because he didn't use the power of the sword to help him...which goes counter to what we saw in the flashback seen in the fire. So it seems like there's a gap that they haven't filled in. Also, they never explain exactly when Dad told Myoga how to split the swords, they never say when his body gets put into the pearl, etc. Still a lot is left out there.</div>