Hi,
I just watched epsiode 80 and wanted to outline my assumption of the "sword collision bug".
On day 79, Casey changed the CanCollide() to check if the collides flag of both entites is set. After that the collision rules are still checked.
So as far as I know, if you set the collides flag of the sword, everything should work again, because it can still go through entites after hitting them due to the the collision rule.