Hmm... I thought I saw Madara use Izanagi against the 1st in the UNS:Generations clip.. must have mistook it for something else then.
How the heck is Izanagi an Uchiha technique if if requires both blood? Unless they inter-bred or something, the offspring of the first 6-Path-Sage did their own thing and should never have encountered the technique. And if they inbred, then Madara's not as special as he's making himself out to be.