When we see Warrick's bare chest he has no scars? We see him slicing himself up earlier in that 8mm film. I don't think THAT was fake. I think he was crazy enough to actually cut himself with a real knife.
But there would have been scars of some kind left over from that wouldn't there?
And the theatrical knives with fake blades also indicates it was faked. It was a bit of a give away when we see him open his shirt and there are no scars.