[ While Scott's seen him heal before, he feels like he needs to drive the point home-- if he doesn't poison his weapon, or get silver, he's not going to be able to fight the monsters that are circling their camp. ]

Not going to pretend to understand it, and I was born a werewolf. It almost... It doesn't reverse the poisoning. More like it stops it, so that the body can heal and get it out of the system.