When I memorize numbers I reinforce them by repeating or using them. This is the sense in which magic reinforces the Shadow.
I have trouble with this. I absolutely believe that drawing on hellfire for his magic causes Harry to reinforce behavioral patterns that are to the shadow's benefit, but I'm not sure why it would reinforce the shadow itself.
If your going to use the word lie than give me a why. I can accept a continuity error, are you suggesting something more?
I'm interested in exploring the priorities of the Knights in general and Michael in particular. Specifically, I'm looking for an answer to the question "to what extent will a Knight do something that they would normally consider wrong to preserve a soul/souls?" We know the answer isn't that they never would, because I can't imagine a world in which Michael thinks that it is right to stand by and let a person be tortured under normal circumstances. We also know that they will refuse to compromise their beliefs most of the time no matter what is at stake, based on their refusal to threaten/kill Cassius themselves and refusal to go after the Denarians preemptively in Small Favor (even though they had taken a hostage and it really would have been a rescue mission).
I want to know where they draw the line, and establishing whether it is more likely than not that Michael has lied to Harry will help answer that.
(I may be slightly biased: I personally believe that letting someone else darken their soul by torturing someone is a worse act than torturing someone yourself, because you're letting someone else be harmed rather than risking yourself. I realize it wasn't intended to be read this way, but emotionally it feels like the Knights were saying that
their souls had more value than those that would be hurt if they did nothing. Having Michael be lying makes me like him more, because it shows that he is human and fallible, just trying to do the best he can to help people even if it's not something he's comfortable with (meaning he didn't think what Harry did to Cassius was actually all that bad, and just objected for form's sake) rather than the perfect paladin who would
never do that (meaning he stood by and let his friend corrupt his soul without even trying to intervene). )
If you can find evidence that Michael wasn't lying, though, I'm fine with that. I've seen one or two explanations posted to that effect that make sense.